CVE-2026-71294: Cotonti CMS Comments Plugin PHP Object Injection via Unrestricted unserialize() in Create/Edit Actions

Severity: high (CVSS 7.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-08-26
Weakness: CWE-502

Description

Cotonti CMS's Comments plugin deserializes user-supplied data without restricting the classes that may be instantiated. In plugins/comments/controllers/actions/CreateAction.php, a POST parameter obtained via (trim-only sanitization) is passed to with no restriction, reachable by any member with write access to comments (the default setting in plugins/comments/comments.setup.php).

Affected products

Cotonti: all versions

References

https://github.com/Cotonti/Cotonti
https://github.com/Cotonti/Cotonti/blob/master/plugins/comments/controllers/actions/CreateAction.php

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