Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch
Unknown · Unknown
5.7MediumCVSS 3.1
Recommended action
Scheduled
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available
Distribution package intelligence
Ubuntu vendor package status
Canonical’s release and source-package findings are shown separately from local repository availability.
1 package state
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
Ubuntu release
Source package
Vendor state
Fixed version
Evidence
Ubuntu 24.04 LTSnoble · standard archive
perl
Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
1 current
CVE-2026-15534 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityperl: Perl: Arbitrary code execution via out-of-bounds memory access in regular expression engine.
322 known affected
The vendor explicitly identifies these products as affected by this CVE.
perl as a component of Red Hat Enterprise Linux 10
perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10
perl-AutoLoader as a component of Red Hat Enterprise Linux 10
perl-AutoSplit as a component of Red Hat Enterprise Linux 10
perl-B as a component of Red Hat Enterprise Linux 10
perl-Benchmark as a component of Red Hat Enterprise Linux 10
perl-Class-Struct as a component of Red Hat Enterprise Linux 10
perl-Config-Extensions as a component of Red Hat Enterprise Linux 10
perl-DBM_Filter as a component of Red Hat Enterprise Linux 10
perl-Devel-Peek as a component of Red Hat Enterprise Linux 10
perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10
perl-DirHandle as a component of Red Hat Enterprise Linux 10
Summary
A flaw was found in Perl. An integer overflow vulnerability in the regular expression engine's superlinear cache calculation can lead to out-of-bounds memory reads and writes. A remote attacker could exploit this by providing a specially crafted, large input string during regular expression matching. This could result in a denial of service (DoS) due to a process crash or potentially lead to heap memory corruption, enabling arbitrary code execution.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2026-54935
No EUVD known-exploited evidence
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.
The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it.
A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
5.7 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Patch available
01
What, why and how
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.
The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it.
A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
What
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.
The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it.
A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
Why
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.
The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it.
A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
Why
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How
An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No confirmed evidence
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.None recorded
No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
Likely attack path
local access → Integer Overflow or Wraparound → disrupt the affected service
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-190: Integer Overflow or Wraparound. The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedDenial of serviceCWE-190
A
Official authority intelligence
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2026-54935Official EUVD mapping
Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch.
The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it.
A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
Official EUVD recordBSI · German · WID-SEC-W-2026-2717Perl: Schwachstelle ermöglicht Denial of Service
Ein Angreifer kann eine Schwachstelle in Perl ausnutzen, um einen Denial of Service Angriff durchzuführen.
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
perl as a component of Red Hat Enterprise Linux 10; perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10; perl-AutoLoader as a component of Red Hat Enterprise Linux 10; perl-AutoSplit as a component of Red Hat Enterprise Linux 10; perl-B as a component of Red Hat Enterprise Linux 10; perl-Benchmark as a component of Red Hat Enterprise Linux 10; perl-Class-Struct as a component of Red Hat Enterprise Linux 10; perl-Config-Extensions as a component of Red Hat Enterprise Linux 10; perl-DBM_Filter as a component of Red Hat Enterprise Linux 10; perl-Devel-Peek as a component of Red Hat Enterprise Linux 10; perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10; perl-DirHandle as a component of Red Hat Enterprise Linux 10; perl-Dumpvalue as a component of Red Hat Enterprise Linux 10; perl-DynaLoader as a component of Red Hat Enterprise Linux 10; perl-English as a component of Red Hat Enterprise Linux 10; perl-Errno as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Constant as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Miniperl as a component of Red Hat Enterprise Linux 10; perl-Fcntl as a component of Red Hat Enterprise Linux 10; perl-File-Basename as a component of Red Hat Enterprise Linux 10; perl-File-Compare as a component of Red Hat Enterprise Linux 10; perl-File-Copy as a component of Red Hat Enterprise Linux 10; perl-File-DosGlob as a component of Red Hat Enterprise Linux 10; perl-File-Find as a component of Red Hat Enterprise Linux 10; perl-File-stat as a component of Red Hat Enterprise Linux 10; perl-FileCache as a component of Red Hat Enterprise Linux 10; perl-FileHandle as a component of Red Hat Enterprise Linux 10; perl-FindBin as a component of Red Hat Enterprise Linux 10; perl-GDBM_File as a component of Red Hat Enterprise Linux 10; and 292 more
Fixed
perl-main@aarch64 as a component of Red Hat Hardened Images; perl-main@noarch as a component of Red Hat Hardened Images; perl-main@src as a component of Red Hat Hardened Images; perl-main@x86_64 as a component of Red Hat Hardened Images
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 9 Aug 2026 · Last source change 8 Sept 2026, 21:31 UTC · CWE-190 · Integer Overflow or Wraparound
CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-54935
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Affected versionsThe structured affected or fixed version information changed.
Before
perl as a component of Red Hat Enterprise Linux 10; perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10; perl-AutoLoader as a component of Red Hat Enterprise Linux 10; perl-AutoSplit as a component of Red Hat Enterprise Linux 10; perl-B as a component of Red Hat Enterprise Linux 10; perl-Benchmark as a component of Red Hat Enterprise Linux 10; perl-Class-Struct as a component of Red Hat Enterprise Linux 10; perl-Config-Extensions as a component of Red Hat Enterprise Linux 10; perl-DBM_Filter as a component of Red Hat Enterprise Linux 10; perl-Devel-Peek as a component of Red Hat Enterprise Linux 10; perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10; perl-DirHandle as a component of Red Hat Enterprise Linux 10; perl-Dumpvalue as a component of Red Hat Enterprise Linux 10; perl-DynaLoader as a component of Red Hat Enterprise Linux 10; perl-English as a component of Red Hat Enterprise Linux 10; perl-Errno as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Constant as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Miniperl as a component of Red Hat Enterprise Linux 10; perl-Fcntl as a component of Red Hat Enterprise Linux 10; perl-File-Basename as a component of Red Hat Enterprise Linux 10; perl-File-Compare as a component of Red Hat Enterprise Linux 10; perl-File-Copy as a component of Red Hat Enterprise Linux 10; perl-File-DosGlob as a component of Red Hat Enterprise Linux 10; perl-File-Find as a component of Red Hat Enterprise Linux 10; perl-File-stat as a component of Red Hat Enterprise Linux 10; perl-FileCache as a component of Red Hat Enterprise Linux 10; perl-FileHandle as a component of Red Hat Enterprise Linux 10; perl-FindBin as a component of Red Hat Enterprise Linux 10; perl-GDBM_File as a component of Red Hat Enterprise Linux 10; and 293 more
After
perl as a component of Red Hat Enterprise Linux 10; perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10; perl-AutoLoader as a component of Red Hat Enterprise Linux 10; perl-AutoSplit as a component of Red Hat Enterprise Linux 10; perl-B as a component of Red Hat Enterprise Linux 10; perl-Benchmark as a component of Red Hat Enterprise Linux 10; perl-Class-Struct as a component of Red Hat Enterprise Linux 10; perl-Config-Extensions as a component of Red Hat Enterprise Linux 10; perl-DBM_Filter as a component of Red Hat Enterprise Linux 10; perl-Devel-Peek as a component of Red Hat Enterprise Linux 10; perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10; perl-DirHandle as a component of Red Hat Enterprise Linux 10; perl-Dumpvalue as a component of Red Hat Enterprise Linux 10; perl-DynaLoader as a component of Red Hat Enterprise Linux 10; perl-English as a component of Red Hat Enterprise Linux 10; perl-Errno as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Constant as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Miniperl as a component of Red Hat Enterprise Linux 10; perl-Fcntl as a component of Red Hat Enterprise Linux 10; perl-File-Basename as a component of Red Hat Enterprise Linux 10; perl-File-Compare as a component of Red Hat Enterprise Linux 10; perl-File-Copy as a component of Red Hat Enterprise Linux 10; perl-File-DosGlob as a component of Red Hat Enterprise Linux 10; perl-File-Find as a component of Red Hat Enterprise Linux 10; perl-File-stat as a component of Red Hat Enterprise Linux 10; perl-FileCache as a component of Red Hat Enterprise Linux 10; perl-FileHandle as a component of Red Hat Enterprise Linux 10; perl-FindBin as a component of Red Hat Enterprise Linux 10; perl-GDBM_File as a component of Red Hat Enterprise Linux 10; and 292 more · Fixed: perl-main@aarch64 as a component of Red Hat Hardened Images; perl-main@noarch as a component of Red Hat Hardened Images; perl-main@src as a component of Red Hat Hardened Images; perl-main@x86_64 as a component of Red Hat Hardened Images
Affected versionsThe structured affected or fixed version information changed.
Before
perl as a component of Red Hat Enterprise Linux 10; perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10; perl-AutoLoader as a component of Red Hat Enterprise Linux 10; perl-AutoSplit as a component of Red Hat Enterprise Linux 10; perl-B as a component of Red Hat Enterprise Linux 10; perl-Benchmark as a component of Red Hat Enterprise Linux 10; perl-Class-Struct as a component of Red Hat Enterprise Linux 10; perl-Config-Extensions as a component of Red Hat Enterprise Linux 10; perl-DBM_Filter as a component of Red Hat Enterprise Linux 10; perl-Devel-Peek as a component of Red Hat Enterprise Linux 10; perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10; perl-DirHandle as a component of Red Hat Enterprise Linux 10; perl-Dumpvalue as a component of Red Hat Enterprise Linux 10; perl-DynaLoader as a component of Red Hat Enterprise Linux 10; perl-English as a component of Red Hat Enterprise Linux 10; perl-Errno as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Constant as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Miniperl as a component of Red Hat Enterprise Linux 10; perl-Fcntl as a component of Red Hat Enterprise Linux 10; perl-File-Basename as a component of Red Hat Enterprise Linux 10; perl-File-Compare as a component of Red Hat Enterprise Linux 10; perl-File-Copy as a component of Red Hat Enterprise Linux 10; perl-File-DosGlob as a component of Red Hat Enterprise Linux 10; perl-File-Find as a component of Red Hat Enterprise Linux 10; perl-File-stat as a component of Red Hat Enterprise Linux 10; perl-FileCache as a component of Red Hat Enterprise Linux 10; perl-FileHandle as a component of Red Hat Enterprise Linux 10; perl-FindBin as a component of Red Hat Enterprise Linux 10; perl-GDBM_File as a component of Red Hat Enterprise Linux 10; and 292 more
After
perl as a component of Red Hat Enterprise Linux 10; perl-Attribute-Handlers as a component of Red Hat Enterprise Linux 10; perl-AutoLoader as a component of Red Hat Enterprise Linux 10; perl-AutoSplit as a component of Red Hat Enterprise Linux 10; perl-B as a component of Red Hat Enterprise Linux 10; perl-Benchmark as a component of Red Hat Enterprise Linux 10; perl-Class-Struct as a component of Red Hat Enterprise Linux 10; perl-Config-Extensions as a component of Red Hat Enterprise Linux 10; perl-DBM_Filter as a component of Red Hat Enterprise Linux 10; perl-Devel-Peek as a component of Red Hat Enterprise Linux 10; perl-Devel-SelfStubber as a component of Red Hat Enterprise Linux 10; perl-DirHandle as a component of Red Hat Enterprise Linux 10; perl-Dumpvalue as a component of Red Hat Enterprise Linux 10; perl-DynaLoader as a component of Red Hat Enterprise Linux 10; perl-English as a component of Red Hat Enterprise Linux 10; perl-Errno as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Constant as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 10; perl-ExtUtils-Miniperl as a component of Red Hat Enterprise Linux 10; perl-Fcntl as a component of Red Hat Enterprise Linux 10; perl-File-Basename as a component of Red Hat Enterprise Linux 10; perl-File-Compare as a component of Red Hat Enterprise Linux 10; perl-File-Copy as a component of Red Hat Enterprise Linux 10; perl-File-DosGlob as a component of Red Hat Enterprise Linux 10; perl-File-Find as a component of Red Hat Enterprise Linux 10; perl-File-stat as a component of Red Hat Enterprise Linux 10; perl-FileCache as a component of Red Hat Enterprise Linux 10; perl-FileHandle as a component of Red Hat Enterprise Linux 10; perl-FindBin as a component of Red Hat Enterprise Linux 10; perl-GDBM_File as a component of Red Hat Enterprise Linux 10; and 293 more
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
CVE-2026-15534: Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch | BlackTree
