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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 9
https://b2evolution.net/news/2022/03/26/2022-update-eol
disclosure@vulncheck.com
https://gist.github.com/axg11/3e29501c33f6e1e05ac2a00107afd64e
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution/blob/7.2.5/htsrv/call_plugin.php#L49
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution/blob/7.2.5/inc/_core/_param.funcs.ph…
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution/commit/25c21cf9cc4261324001f90395097…
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution/commit/335abf09bcea61717bd00bc1e3889…
disclosure@vulncheck.com
https://github.com/b2evolution/b2evolution/commit/999b5ad1d59760d7e450ceb541f55…
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/b2evolution-cms-6.7.8-through-7.2.5-object…
disclosure@vulncheck.com