# CVE-2026-91939

## Summary

- **CVE ID:** CVE-2026-91939
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-502
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 16, 2026

## Description

Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads to trigger gadget chains and achieve database manipulation or code execution.

## Affected Products

- Cotonti — Cotonti (1.0.0)

## References

- [CNA](https://github.com/Cotonti/Cotonti/issues/1888)
- [CNA](https://github.com/Cotonti/Cotonti/pull/1889)
- [CNA](https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/inc/CommentsWidget.php)
- [CNA](https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/controllers/actions/DisplayAction.php)
- [CNA](https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/comments.setup.php)
- [CNA](https://github.com/Cotonti/Cotonti)
- [CNA](https://www.vulncheck.com/advisories/cotonti-1.0.0-comments-plugin-php-object-injection-via-ci-parameter)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.59%
- **EPSS Percentile:** 46.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._