Quick answers
- Is CVE-2026-7259 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-7259 being exploited in the wild.
- How severe is CVE-2026-7259?
- Medium severity, with a CVSS score of 6.5, published 10 May 2026.
- Which products and versions are affected?
- PHP Group PHP 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, 8.5.* before 8.5.6, 8.2.0 to 8.2.30, 8.3.0 to 8.3.30, 8.4.0 to 8.4.20, 8.5.0 to 8.5.5.
- Is there a fix for CVE-2026-7259?
- A patch was published on 2026-05-10: Patched versions released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-7259 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-7259?
- Check whether you run PHP Group PHP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A mismatch exists between the encoding lists supported by the Oniguruma regex library and the internal mbfl library within PHP's mbstring extension. When mb_regex_encoding() is called with an encoding supported by Oniguruma but not by mbfl (such as 'iso-8859-11'), the internal mbfl encoding pointer is set to NULL. Subsequent calls to mbregex search APIs, such as mb_ereg_search_init(), result in a NULL pointer dereference in php_mb_check_encoding(). This leads to a segmentation fault and process crash. The issue is fixed in PHP versions 8.2.31, 8.3.31, 8.4.21, and 8.5.6.
Affected products
- PHP Group PHP 8.2.0 to 8.2.30, 8.3.0 to 8.3.30, 8.4.0 to 8.4.20, 8.5.0 to 8.5.5
Timeline
- 2026-05-07: advisory: GitHub Security Advisory published by PHP Group
- 2026-05-10: disclosed: CVE published to NVD
- 2026-05-10: patched: Patched versions released