CVE-2026-51953: FeehiCMS Privilege Escalation Flaw

CVE-2026-51953 Overview

CVE-2026-51953 is a privilege escalation vulnerability in FeehiCMS v2.1.1. The flaw resides in the session management module, authentication logic, and logout handler components. An unauthenticated network attacker can abuse improper session handling to gain elevated privileges within the application. The issue is categorized under CWE-613: Insufficient Session Expiration, indicating that session tokens remain valid beyond their intended lifetime. FeehiCMS is an open-source content management system maintained in the liufee/cms GitHub repository.

Critical Impact
Attackers can escalate privileges over the network without authentication, compromising confidentiality and integrity of FeehiCMS-managed content.

Affected Products

FeehiCMS v2.1.1
FeehiCMS session management module
FeehiCMS authentication and logout handler components

Discovery Timeline

2026-07-31 - CVE-2026-51953 published to NVD
2026-08-03 - Last updated in NVD database

Technical Details for CVE-2026-51953

Vulnerability Analysis

The vulnerability affects three interconnected components in FeehiCMS v2.1.1: the session management module, the authentication logic, and the logout handler. Together these components govern how user sessions are created, validated, and terminated. Improper handling across these code paths permits an attacker to reach a privileged application state without proper credential validation. The flaw is exploitable over the network and requires no user interaction, though attack complexity is rated high because specific conditions must be met to trigger the escalation path.

Root Cause

The root cause is insufficient session expiration [CWE-613]. Session identifiers issued by FeehiCMS are not correctly invalidated across the authentication and logout flows. When a user logs out, the corresponding session token remains usable, allowing continued access with previously granted privileges. Combined with weaknesses in the authentication logic, this residual session state enables an attacker to assume the identity of another user or elevate to an administrative role.

Attack Vector

Exploitation occurs remotely over HTTP against the FeehiCMS web interface. An attacker who obtains or predicts a valid session identifier through observation, interception, or reuse after logout can replay the token to access authenticated endpoints. Because the logout handler fails to destroy server-side session state, previously captured tokens continue to authorize privileged operations. Successful exploitation results in high impact to confidentiality and integrity, with no direct availability impact.

No public proof-of-concept code has been released. Technical details are described in the CVE-2026-51953 documentation on GitHub.

Detection Methods for CVE-2026-51953

Indicators of Compromise

Session cookies observed in HTTP traffic after a documented logout event for the same user account.
Administrative actions performed from source IP addresses that differ from the original login IP for a given session ID.
Reuse of the same PHPSESSID or FeehiCMS session token across disparate user-agent strings.
Unexpected role changes or content modifications in FeehiCMS audit logs without corresponding authentication events.

Detection Strategies

Correlate authentication, logout, and privileged action events to identify sessions that remain active past logout.
Alert on privileged endpoints accessed with session tokens whose issuing account has logged out.
Track session token lifetime distributions and flag tokens exceeding configured expiration windows.

Monitoring Recommendations

Enable verbose logging on FeehiCMS authentication and session-management endpoints.
Forward web server access logs to a centralized SIEM for correlation of session identifiers, source IPs, and user agents.
Monitor for anomalous privilege escalation actions such as new administrator account creation or role modifications.

How to Mitigate CVE-2026-51953

Immediate Actions Required

Restrict network access to FeehiCMS administrative interfaces using firewall rules or reverse-proxy allowlists.
Force invalidation of all active sessions and require users to re-authenticate.
Rotate session encryption keys and cookie signing secrets used by FeehiCMS.
Audit administrator accounts and recent privileged actions for unauthorized changes.

Patch Information

At the time of publication, no vendor patch is referenced in the NVD entry for CVE-2026-51953. Monitor the liufee/cms GitHub repository for updated releases addressing the session management, authentication, and logout components.

Workarounds

Configure the web server or application to enforce short session lifetimes and idle timeouts.
Terminate server-side session state explicitly on logout by clearing session storage in addition to unsetting cookies.
Bind session tokens to client attributes such as source IP or user-agent to reduce token replay viability.
Place FeehiCMS behind a reverse proxy that enforces authentication and session validation independently.

bash

# Configuration example: enforce shorter PHP session lifetime and secure cookies
session.gc_maxlifetime = 900
session.cookie_lifetime = 0
session.cookie_secure = 1
session.cookie_httponly = 1
session.cookie_samesite = "Strict"
session.use_strict_mode = 1