Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers… (CVE-2026-91939)
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.
AI Analysis
Technical Summary
The vulnerability in Cotonti 1.0.0 Comments plugin arises from unsafe usage of the unserialize() function on user-supplied input via the 'ci' GET parameter without applying the allowed_classes restriction. This enables attackers to instantiate arbitrary PHP objects with attacker-controlled properties, facilitating exploitation through gadget chains that can result in high-impact outcomes such as database manipulation or code execution.
Potential Impact
Successful exploitation can lead to full compromise of the affected system, including unauthorized database manipulation and remote code execution. The vulnerability has a CVSS 3.1 score of 9.8, indicating critical severity with network attack vector, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
No patch or official fix information is provided. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid exposing the vulnerable 'ci' parameter or restrict access to the Comments plugin. Consider applying web application firewall rules to detect and block malicious serialized payloads targeting this vulnerability.
Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers… (CVE-2026-91939)
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.
CVSS v3.1
Score 9.8critical
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Cotonti 1.0.0 Comments plugin arises from unsafe usage of the unserialize() function on user-supplied input via the 'ci' GET parameter without applying the allowed_classes restriction. This enables attackers to instantiate arbitrary PHP objects with attacker-controlled properties, facilitating exploitation through gadget chains that can result in high-impact outcomes such as database manipulation or code execution.
Potential Impact
Successful exploitation can lead to full compromise of the affected system, including unauthorized database manipulation and remote code execution. The vulnerability has a CVSS 3.1 score of 9.8, indicating critical severity with network attack vector, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability.
Mitigation Recommendations
No patch or official fix information is provided. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid exposing the vulnerable 'ci' parameter or restrict access to the Comments plugin. Consider applying web application firewall rules to detect and block malicious serialized payloads targeting this vulnerability.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-xv9c-9hwm-jp8g
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-91939"]
- Database Specific Severity
- CRITICAL
- Cvss Version
- 3.1
Threat ID: 6aaa07d255bf5e2cf5ea26e9
Added to database: 09/16/2026, 03:06:58 UTC
Last enriched: 09/16/2026, 03:14:27 UTC
Last updated: 09/16/2026, 22:01:39 UTC
Views: 4
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