CVE-2026-76834 PUBLISHED

b2evolution CMS versions 6.7.8 through 7.2.5 contain an incomplete fix for CVE-2016-8901 where the serialized-array object check in param_check_serialized_array() fails to reject payloads with negative integer array keys. Unauthenticated attackers can submit crafted serialized PHP objects via POST requests to htsrv/call_plugin.php that bypass validation and reach unserialize(), instantiating arbitrary PHP objects with attacker-chosen properties that may enable code execution if suitable POP gadget chains exist.

• Adrian Gaitan finder
• VulnCheck coordinator

• https://gist.github.com/axg11/3e29501c33f6e1e05ac2a00107afd64e
• https://github.com/b2evolution/b2evolution/blob/7.2.5/inc/_core/_param.funcs.php#L2860
• https://github.com/b2evolution/b2evolution/blob/7.2.5/htsrv/call_plugin.php#L49
• Incomplete fix for CVE-2016-8901 (1 of 2)
• Incomplete fix for CVE-2016-8901 (2 of 2)
• Introduces the flawed regular expression, first released in 6.7.8
• b2evolution CMS end-of-life announcement
• https://github.com/b2evolution/b2evolution
• VulnCheck Advisory: b2evolution CMS 6.7.8 through 7.2.5 Object Injection via Negative Integer Array Key

• Deserialization of Untrusted Data CWE