CVE-2026-55867: CWE-639: Authorization Bypass Through User-Controlled Key in Graylog2 graylog2-server
Description
CVE-2026-55867 is a medium severity authorization bypass vulnerability in Graylog2's graylog2-server affecting versions from 6.2.0 until fixed in 6.3.12, 7.0.7, and 7.1.2. It allows an authenticated user to delete access tokens belonging to other users, including service accounts or administrators, by exploiting improper permission checks on the DELETE /users/{userId}/tokens/{idOrToken} endpoint. The vulnerability does not expose token contents but can disrupt access-token-based integrations by unauthorized token deletion.
CVSS v4.0
Score 5.3medium
Affected software
Graylog2
graylog2-server
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability exists in the UsersResource.revokeToken() method of graylog2-server, where the USERS_TOKENREMOVE permission is checked against the userId path parameter controlled by the attacker before resolving the token identified by idOrToken. Because the token resolution does not verify that the token belongs to the authorized user, an attacker can delete tokens of other users, including privileged accounts. This causes an integrity impact by disrupting token-based access controls. The issue is fixed in Graylog2 versions 6.3.12, 7.0.7, and 7.1.2.
Potential Impact
An authenticated user can delete access tokens of other users without proper authorization, including tokens of service accounts or administrators. This unauthorized deletion can disrupt access-token-based integrations and cause integrity issues by invalidating tokens unexpectedly. The vulnerability does not expose token contents or allow token misuse beyond deletion.
Mitigation Recommendations
This vulnerability is fixed in Graylog2 versions 6.3.12, 7.0.7, and 7.1.2. Users should upgrade to one of these versions or later to remediate the issue. No other vendor advisories or temporary mitigations are provided. Patch status is confirmed by the vendor's fixed versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-17T16:44:40.996Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a920a36acd9273b4968cbf2
Added to database: 08/28/2026, 22:22:46 UTC
Last enriched: 09/07/2026, 15:27:25 UTC
Last updated: 10/12/2026, 06:48:17 UTC
Views: 97
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.