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Full vulnerability report · 2026
CVE-2026-17544High confidence

Out-of-bounds write in bccomp() via crafted operand and scale

PHP Group · PHP

8.1HighCVSS 4.0
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Direct vendor intelligence

Authoritative 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.

1 current
CVE-2026-17544 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityphp: PHP: Arbitrary code execution via out-of-bounds write in bccomp()
28 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • php as a component of Red Hat Enterprise Linux 6
  • php-bcmath as a component of Red Hat Enterprise Linux 6
  • php-cli as a component of Red Hat Enterprise Linux 6
  • php-common as a component of Red Hat Enterprise Linux 6
  • php-dba as a component of Red Hat Enterprise Linux 6
  • php-devel as a component of Red Hat Enterprise Linux 6
  • php-embedded as a component of Red Hat Enterprise Linux 6
  • php-enchant as a component of Red Hat Enterprise Linux 6
  • php-fpm as a component of Red Hat Enterprise Linux 6
  • php-gd as a component of Red Hat Enterprise Linux 6
  • php-imap as a component of Red Hat Enterprise Linux 6
  • php-intl as a component of Red Hat Enterprise Linux 6
Summary
A flaw was found in PHP. A remote attacker could exploit this vulnerability by providing specially crafted inputs to the `bccomp()` function. This could lead to an out-of-bounds write, resulting in stack and heap corruption. Such memory corruption can enable arbitrary code execution, allowing the attacker to take control of the affected system.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
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-2026-51091

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.* before 8.5.9.

What

Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.* before 8.5.9.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

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

Attacker-provided inputs to bccomp() could lead to an out-of-bounds write with stack and heap corruption in PHP versions from 8.4.* before 8.4.24 and from 8.5.* before 8.5.9.

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

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
?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
a network path → Out-of-bounds Write → 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
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-787 ↗

CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/AU:N

Common Vulnerability Scoring System 4.0: 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
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.
NetworkUnauthenticatedCWE-787
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2026-2598PHP: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in PHP ausnutzen, um SQL-Injection durchzuführen, beliebigen Code auszuführen, Daten zu manipulieren oder einen Denial-of-Service-Zustand auszulösen.

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0952Multiples vulnérabilités dans PHP

De multiples vulnérabilités ont été découvertes dans PHP. Certaines d'entre elles permettent à un attaquant de provoquer une injection SQL (SQLi), un déni de service et un problème de sécurité non spécifié par l'éditeur.

Official advisory
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.
Patch available
Affected
php as a component of Red Hat Enterprise Linux 6; php-bcmath as a component of Red Hat Enterprise Linux 6; php-cli as a component of Red Hat Enterprise Linux 6; php-common as a component of Red Hat Enterprise Linux 6; php-dba as a component of Red Hat Enterprise Linux 6; php-devel as a component of Red Hat Enterprise Linux 6; php-embedded as a component of Red Hat Enterprise Linux 6; php-enchant as a component of Red Hat Enterprise Linux 6; php-fpm as a component of Red Hat Enterprise Linux 6; php-gd as a component of Red Hat Enterprise Linux 6; php-imap as a component of Red Hat Enterprise Linux 6; php-intl as a component of Red Hat Enterprise Linux 6; php-ldap as a component of Red Hat Enterprise Linux 6; php-mbstring as a component of Red Hat Enterprise Linux 6; php-mysql as a component of Red Hat Enterprise Linux 6; php-odbc as a component of Red Hat Enterprise Linux 6; php-pdo as a component of Red Hat Enterprise Linux 6; php-pgsql as a component of Red Hat Enterprise Linux 6; php-process as a component of Red Hat Enterprise Linux 6; php-pspell as a component of Red Hat Enterprise Linux 6; php-recode as a component of Red Hat Enterprise Linux 6; php-snmp as a component of Red Hat Enterprise Linux 6; php-soap as a component of Red Hat Enterprise Linux 6; php-tidy as a component of Red Hat Enterprise Linux 6; php-xml as a component of Red Hat Enterprise Linux 6; php-xmlrpc as a component of Red Hat Enterprise Linux 6; php-zts as a component of Red Hat Enterprise Linux 6; php.src as a component of Red Hat Enterprise Linux 6
Fixed
php8.4-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-0:8.4.24-1.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-debuginfo-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-debuginfo-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-debuginfo-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-bcmath-debuginfo-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-debuginfo-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-debuginfo-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-debuginfo-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-cli-debuginfo-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-debuginfo-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-debuginfo-0:8.4.24-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-debuginfo-0:8.4.24-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-common-debuginfo-0:8.4.24-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); php8.4-dba-0:8.4.24-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); and 174 more
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 30 Jul 2026 · Last source change 31 Jul 2026, 03:55 UTC · CWE-787 · Out-of-bounds Write

CVE recordCVE.org · 5.2
CVSS sourceCNA
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-2026-51091
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-51091↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
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.
Free version - for non-commercial use only.CVE-2026-17544 · cve.blacktree.nl