With catch_workers_output enabled, worker output can pollute the FPM log or remove up to four characters from log messages.
Affected versions
| Branch | Affected | Fixed in |
|---|---|---|
| PHP 8.3 | < 8.3.12 | 8.3.12 |
| PHP 8.2 | < 8.2.24 | 8.2.24 |
| PHP 8.1 | < 8.1.30 | 8.1.30 |
Older branches: not assessed
Exploitation conditions
- catch_workers_output = yes (disabled by default)
Remediation
Upgrade to 8.1.30, 8.2.24, 8.3.12 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 |
|---|---|---|
| 3.3 v3.1 | NVD | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N |
References
Data provenance
Secondary sources · pending primary verificationLast reviewed: Oct 24, 2026 · Source