Segfault DoS: PHP 8.28.5 via mb_regex_encoding NULL ptr deref
CVE-2026-7259 Published on May 10, 2026
Null pointer dereference in php_mb_check_encoding() via mb_ereg_search_init()
In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, a mismatch between encoding lists in Oniguruma and mbfl leads to a NULL pointer dereference, resulting in a segmentation fault and denial of service. The vulnerability is exploitable when user-controlled input can influence the encoding passed to mb_regex_encoding().
Vulnerability Analysis
CVE-2026-7259 can be exploited with network access. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
NULL Pointer Dereference
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions.
Products Associated with CVE-2026-7259
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Affected Versions
PHP Group PHP:- Version 8.2.* and below 8.2.31 is affected.
- Version 8.3.* and below 8.3.31 is affected.
- Version 8.4.* and below 8.4.21 is affected.
- Version 8.5.* and below 8.5.6 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.