An integer overflow in the element count of array_merge() leads to a heap buffer overflow.
Affected versions
| Branch | Affected | Fixed in |
|---|---|---|
| PHP 8.5 | < 8.5.1 | 8.5.1 |
| PHP 8.4 | < 8.4.16 | 8.4.16 |
| PHP 8.3 | < 8.3.29 | 8.3.29 |
| PHP 8.2 | < 8.2.30 | 8.2.30 |
| PHP 8.1 | < 8.1.34 | 8.1.34 |
Older branches: not assessed
Exploitation conditions
No special conditions are documented.
Remediation
Upgrade to 8.1.34, 8.2.30, 8.3.29, 8.4.16, 8.5.1 or a later release of your branch. If your branch is end-of-life, move to a supported branch. Distribution packages may carry a backported fix under an older version number; confirm with your vendor's security tracker.
A version number alone cannot prove patch status. Linux distributions and hosting providers often backport security fixes without changing the version. Check your vendor’s changelog.
Severity scores
| CVSS | Source | Vector |
|---|---|---|
| 8.2 v3.1 | GitHub | — |
References
Data provenance
Secondary sources · pending primary verificationLast reviewed: Oct 24, 2026 · Source
Notes: Score from a single secondary source. Assembled from secondary sources.