Network functions do not reject NUL bytes in hostnames, so validation done with parse_url() and the actual connection can disagree about the target host, bypassing access checks.
Affected versions
| Branch | Affected | Fixed in |
|---|---|---|
| PHP 8.4 | < 8.4.10 | 8.4.10 |
| PHP 8.3 | < 8.3.23 | 8.3.23 |
| PHP 8.2 | < 8.2.29 | 8.2.29 |
| PHP 8.1 | < 8.1.33 | 8.1.33 |
Older branches: not assessed
Exploitation conditions
No special conditions are documented.
Remediation
Upgrade to 8.1.33, 8.2.29, 8.3.23, 8.4.10 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 |
|---|---|---|
| 5.3 v3.1 | NVD | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
References
Data provenance
Secondary sources · pending primary verificationLast reviewed: Oct 24, 2026 · Source
Notes: One source lists a conflicting CVSS v4 score of 9.1.