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Vulnerability record · CVE-2026-76834 · published 17 September 2026

CVE-2026-76834: Deserialization of untrusted data vulnerability

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.

9.2 CVSS 4.0 Critical EPSS 0.85% · top 43.6% CWE-502 · Deserialization of untrusted data Deferred
9.2CVSS 4.0 base score
0.85%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
9References
23 Sep 2026Last modified by NVD

Description

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.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://b2evolution.net/news/2022/03/26/2022-update-eol
https://gist.github.com/axg11/3e29501c33f6e1e05ac2a00107afd64e
https://github.com/b2evolution/b2evolution
https://github.com/b2evolution/b2evolution/blob/7.2.5/htsrv/call_plugin.php#L49
https://github.com/b2evolution/b2evolution/blob/7.2.5/inc/_core/_param.funcs.php#L2860
https://github.com/b2evolution/b2evolution/commit/25c21cf9cc4261324001f9039509710b37ee2c4d
https://github.com/b2evolution/b2evolution/commit/335abf09bcea61717bd00bc1e3889f8100ebd1bb
https://github.com/b2evolution/b2evolution/commit/999b5ad1d59760d7e450ceb541f55432fc74cd27
https://www.vulncheck.com/advisories/b2evolution-cms-6.7.8-through-7.2.5-object-injection-via-negative-integer-array-key

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Source: NIST National Vulnerability Database (record CVE-2026-76834), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.