CVE-2026-91939

Status: DeferredCritical (9.3)—

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

Version: 4.0
Vector: 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/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:X/V:X/RE:X/U:X
Base score: 9.3

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.98%
Percentile among all scored CVEs: 61
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access95 %
Primary impactT1059 Command and Scripting Interpreterexecution85 %
Secondary impactT1565.001 Stored Data Manipulationimpact80 %

Vector AV:N/PR:N/UI:N sin autenticación indica explotación remota T1190. CWE-502 (deserialización insegura en PHP) y 'gadget chains' permiten ejecución de código (T1059) y manipulación de BD (T1565.001).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Privileged Account Management Vulnerability Scanning Restrict Web-Based Content Restrict File and Directory Permissions Remote Data Storage Network Segmentation

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Cotonti — Comments Plugin^AI

CWEs

CWE-502

References

Raw JSON (NVD)

Show

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    {
      "lang": "en",
      "value": "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."
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  "lastModified": "2026-09-16T20:21:01.047",
  "sourceIdentifier": "disclosure@vulncheck.com"
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