Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.48% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-8376High confidence
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds
Unknown · Unknown
9.8CriticalCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 66 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Unknown Unknown and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 66 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 66 affected or under-investigation product states without a fixed product state in the same current advisory
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
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.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | perl | Vendor fix publishedDebian records a fixed source-package version for this release. | 5.40.1-6+deb13u1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | perl | Vendor fix publishedDebian records a fixed source-package version for this release. | 5.36.0-7+deb12u4 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | perl | Vendor fix publishedDebian records a fixed source-package version for this release. | 5.40.1-8 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | perl | Vendor fix publishedDebian records a fixed source-package version for this release. | 5.40.1-8 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | perl | Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree. | 5.38.2-3.2ubuntu0.3 | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-8376 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityperl: Perl: Heap buffer overflow when compiling regular expressions on 32-bit builds
The vendor explicitly identifies these products as affected by this CVE.
- perl as a component of Red Hat Enterprise Linux 6
- perl-Archive-Extract as a component of Red Hat Enterprise Linux 6
- perl-Archive-Tar as a component of Red Hat Enterprise Linux 6
- perl-CGI as a component of Red Hat Enterprise Linux 6
- perl-CPAN as a component of Red Hat Enterprise Linux 6
- perl-CPANPLUS as a component of Red Hat Enterprise Linux 6
- perl-Compress-Raw-Bzip2 as a component of Red Hat Enterprise Linux 6
- perl-Compress-Raw-Zlib as a component of Red Hat Enterprise Linux 6
- perl-Compress-Zlib as a component of Red Hat Enterprise Linux 6
- perl-Digest-SHA as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-CBuilder as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 6
- Summary
- A flaw was found in Perl. A remote attacker could exploit a heap buffer overflow vulnerability when compiling regular expressions with a repeated fixed string on 32-bit builds. Specifically, the `Perl_study_chunk` function in `regcomp_study.c` incorrectly calculates the size of the joined substring buffer, leading to an undersized memory allocation. This allows a subsequent copy operation to write past the end of the buffer, potentially enabling arbitrary code execution or causing a denial of service (DoS).
- Remediation
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 66 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer. A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.
What
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer. A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.
Why
The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer. A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.
Why
The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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
- a network path → Integer Overflow to Buffer Overflow → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- 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-680 ↗
CWE-680: Integer Overflow to Buffer Overflow. The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.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.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
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. - Fix availability varies by product
- Affected
- perl as a component of Red Hat Enterprise Linux 6
- perl-Archive-Extract as a component of Red Hat Enterprise Linux 6
- perl-Archive-Tar as a component of Red Hat Enterprise Linux 6
- perl-CGI as a component of Red Hat Enterprise Linux 6
- perl-CPAN as a component of Red Hat Enterprise Linux 6
- perl-CPANPLUS as a component of Red Hat Enterprise Linux 6
- perl-Compress-Raw-Bzip2 as a component of Red Hat Enterprise Linux 6
- perl-Compress-Raw-Zlib as a component of Red Hat Enterprise Linux 6
- perl-Compress-Zlib as a component of Red Hat Enterprise Linux 6
- perl-Digest-SHA as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-CBuilder as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-Embed as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-MakeMaker as a component of Red Hat Enterprise Linux 6
- perl-ExtUtils-ParseXS as a component of Red Hat Enterprise Linux 6
- perl-File-Fetch as a component of Red Hat Enterprise Linux 6
- perl-IO-Compress-Base as a component of Red Hat Enterprise Linux 6
- perl-IO-Compress-Bzip2 as a component of Red Hat Enterprise Linux 6
- perl-IO-Compress-Zlib as a component of Red Hat Enterprise Linux 6
- perl-IO-Zlib as a component of Red Hat Enterprise Linux 6
- perl-IPC-Cmd as a component of Red Hat Enterprise Linux 6
- perl-Locale-Maketext-Simple as a component of Red Hat Enterprise Linux 6
- perl-Log-Message as a component of Red Hat Enterprise Linux 6
- perl-Log-Message-Simple as a component of Red Hat Enterprise Linux 6
- perl-Module-Build as a component of Red Hat Enterprise Linux 6
- perl-Module-CoreList as a component of Red Hat Enterprise Linux 6
- perl-Module-Load as a component of Red Hat Enterprise Linux 6
- perl-Module-Load-Conditional as a component of Red Hat Enterprise Linux 6
- perl-Module-Loaded as a component of Red Hat Enterprise Linux 6
- perl-Module-Pluggable as a component of Red Hat Enterprise Linux 6
- perl-Object-Accessor as a component of Red Hat Enterprise Linux 6
- and 36 more
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
04
Evidence and provenance
Published 25 May 2026 · Last source change 8 Sept 2026, 21:33 UTC · CWE-680 · Integer Overflow to Buffer Overflow
CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-31772
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment
Missing structured fields: affected product. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- perl: ≤ 5.43.10 · Fixed: Upgrade to a future perl release, or apply the upstream patch.
- After
- < 5.40.5-RC1, 5.41.0 < 5.42.3-RC1, 5.43.0 < 5.43.11 · Fixed: Upgrade to Perl 5.40.5, 5.42.3 or 5.44.0 or later, or apply the upstream patch.
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- ≤ 5.43.10 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- < 5.40.5-RC1; 5.41.0 < 5.42.3-RC1; 5.43.0 < 5.43.11 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- < 5.40.5-RC1; 5.41.0 < 5.42.3-RC1; 5.43.0 < 5.43.11 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- perl: ≤ 5.43.10 · Fixed: Upgrade to a future perl release, or apply the upstream patch.
CVE published
Fixed release or patch reference recorded
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.