CVE-2026-120007 in NodeBB
Summary
by MITRE • 10/30/2026
NodeBB 1.18.0 through 4.16.5 contains an authorization bypass vulnerability that allows unauthenticated visitors to act on other accounts by supplying a uid during POST /register. Attackers can submit an empty email at the /register/complete interstitial to clear a victim's email and confirmation state and revoke all their sessions.
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Analysis
by VulDB Data Team • 10/30/2026
NodeBB, a popular open-source forum software built on Node.js, suffers from a critical authorization bypass vulnerability in versions 1.18.0 through 4.16.5 that fundamentally undermines the integrity of user account management. The core technical flaw resides within the registration and session handling mechanisms, specifically where the application fails to properly validate ownership or context when processing POST requests directed at the /register endpoint with a supplied uid parameter. This design oversight allows an unauthenticated attacker to inject arbitrary user identifiers into the request payload, effectively tricking the server into associating actions intended for new account creation or modification with existing victim accounts rather than creating isolated entities as designed.
The exploitation of this vulnerability enables attackers to perform unauthorized state changes on targeted user profiles without possessing valid credentials or session tokens. By supplying a specific uid during the registration process, an attacker can manipulate backend logic that assumes the provided identifier belongs to the actor initiating the request. This lack of server-side verification regarding the relationship between the requester and the target uid creates a severe privilege escalation path where unauthenticated users gain the ability to alter account attributes belonging to other registered members. The vulnerability is particularly insidious because it operates during what appears to be standard user onboarding flows, making detection by automated security monitoring tools more difficult as the traffic resembles legitimate registration attempts.
The operational impact of this flaw extends beyond simple data modification and includes a complete compromise of session integrity for affected users. Attackers can exploit an interstitial step at /register/complete to submit empty email addresses for victim accounts. This action effectively clears the victim's registered email address and resets their confirmation state, which serves as a critical trust indicator within the platform's authentication workflow. By stripping these essential identity markers, the attacker disrupts the user's ability to receive password reset links or verification notifications, thereby locking them out of legitimate account recovery processes. Furthermore, this manipulation triggers a cascade effect that revokes all active sessions associated with the compromised uid, forcing immediate logout and disrupting ongoing interactions within the forum environment.
From an industry standard perspective, this vulnerability aligns closely with CWE-287, which describes Improper Authentication, as well as CWE-306, Missing Authentication for Critical Function. The specific technique of manipulating user identifiers to affect other accounts is characteristic of IDOR (Insecure Direct Object Reference) patterns often categorized under CWE-639 if the authorization check relies solely on client-supplied data rather than server-side session validation. In terms of MITRE ATT&CK, this behavior maps to T1078 Valid Accounts and potentially T1534 Internal Spearphishing if used in conjunction with social engineering, though primarily it represents a direct exploitation of access control mechanisms (T1098). The ability to revoke sessions also impacts the availability aspect of security by causing denial of service for legitimate users through forced logouts.
Mitigation strategies must prioritize immediate patching to versions 4.16.6 or later where these authorization checks have been corrected. In environments where upgrading is not immediately feasible, administrators should implement strict input validation on all uid parameters within registration endpoints to ensure they match the authenticated user's identity if authentication were required, or reject such parameters entirely for unauthenticated requests since new registrations should not require existing uids. Additionally, deploying a Web Application Firewall with rules that detect anomalous patterns in POST data containing unexpected numeric identifiers during registration flows can provide temporary protection against exploitation attempts while longer-term architectural fixes are implemented to enforce strict separation between user identity and request context.