CVE-2026-55867: Graylog2 server Graylog Token Revocation Endpoint Allows Vulnerability

Q: What is CVE-2026-55867?

CVE-2026-55867 is a security vulnerability in Graylog2 server involving Graylog token revocation endpoint allows authenticated users to delete other users’ access tokens under CWE-639: Authorization Bypass Through User-Controlled Key.

Q: Which Graylog2 server versions are affected?

Affected versions include releases prior to 6.3.12, 7.0.7, 7.1.2 across affected packages: org.graylog2:graylog2-server.

Q: What version fixes CVE-2026-55867?

Upgrading to 6.3.12, 7.0.7, 7.1.2 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is graylog2-server affected?

Yes, org.graylog2:graylog2-server is affected in releases prior to 6.3.12, 7.0.7, 7.1.2. Upgrade your dependency to 6.3.12, 7.0.7, 7.1.2 or later.

Q: What CWE is associated with CVE-2026-55867?

CVE-2026-55867 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).

Q: How can I check Maven dependencies for CVE-2026-55867?

Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.graylog2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

MODERATE

Advisory Identifier: GHSA-j769-9gv9-65gr

CWE-639

Published 2026-08-28

Advisory Summary

CVE-2026-55867 is a MODERATE graylog token revocation endpoint allows vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Graylog2 server libraries in the Maven ecosystem. The issue involves graylog token revocation endpoint allows authenticated users to delete other users’ access tokens. Remediation is available by upgrading affected packages to version 6.3.12, 7.0.7, 7.1.2.

CVE-2026-55867 at a Glance

CVE Identifier CVE-2026-55867

GHSA Identifier GHSA-j769-9gv9-65gr

Severity MODERATE

CVSS v3.1 Base Score N/A

CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key

Affected Product Graylog2 server

Package Ecosystem Maven

Published Date 2026-08-28

Last Updated 2026-08-28

How to Fix CVE-2026-55867

To remediate this vulnerability, upgrade all affected Graylog2 server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.graylog2:graylog2-server fixed: 6.3.12

<dependency>
    <groupId>org.graylog2</groupId>
    <artifactId>graylog2-server</artifactId>
    <version>6.3.12</version>
</dependency>

org.graylog2:graylog2-server fixed: 7.0.7

<dependency>
    <groupId>org.graylog2</groupId>
    <artifactId>graylog2-server</artifactId>
    <version>7.0.7</version>
</dependency>

org.graylog2:graylog2-server fixed: 7.1.2

<dependency>
    <groupId>org.graylog2</groupId>
    <artifactId>graylog2-server</artifactId>
    <version>7.1.2</version>
</dependency>

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

mvn dependency:tree -Dincludes=org.graylog2

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-55867, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.graylog2

Analyze the terminal output to locate any version of Graylog2 server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.3.12), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.graylog2 command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In Graylog2 server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Graylog contains an insecure direct object reference (IDOR) vulnerability in the token revocation endpoint. An authenticated user can delete access tokens belonging to other users, including service account tokens and administrator tokens, if they know or can guess a valid token identifier. The issue does not expose token contents, but it allows unauthorized token deletion, leading to integrity impact and potential availability impact for access token based integrations. ### Patches The issue has been fixed in the following Graylog versions: `6.3.12`, `7.0.7`, `7.1.2`. Users should upgrade to one of these versions or above to remediate the vulnerability. Graylog Cloud has already been patched. ### Workarounds There are no feasible workarounds for this issue. Upgrading to a patched version is recommended. Customers using Graylog Enterprise or Security can review the audit log[^1] for suspicious activity. Audit log lines for successful token deletions begin with `access token deleted from user`. ### Credits Thanks to [michaelddickenson](https://github.com/michaelddickenson) and [sreelim](https://github.com/sreelim) for reporting. [^1]: https://go2docs.graylog.org/current/interacting_with_your_log_data/audit_log.html

CVE-2026-55867 Affected Graylog2 server Versions

3 component(s)

Fixed Versions:

6.3.127.0.77.1.2

Product / Package	Ecosystem	Affected Versions	Fixed Version
org.graylog2:graylog2-server maven/org.graylog2/graylog2-server	Maven	≥ 6.2.0 < 6.3.12	6.3.12
org.graylog2:graylog2-server maven/org.graylog2/graylog2-server	Maven	≥ 7.0.0 < 7.0.7	7.0.7
org.graylog2:graylog2-server maven/org.graylog2/graylog2-server	Maven	≥ 7.1.0 < 7.1.2	7.1.2

References

GitHub Advisory / Wiki ADVISORY

https://github.com/Graylog2/graylog2-server/security/advisories/GHSA-j769-9gv9-65gr

Graylog2 server Source Repository REPOSITORY

https://github.com/Graylog2/graylog2-server/pull/26049

Graylog2 server Source Repository REPOSITORY

https://github.com/Graylog2/graylog2-server/pull/26051

Graylog2 server Source Repository REPOSITORY

https://github.com/Graylog2/graylog2-server/pull/26053

Graylog2 server Source Repository REPOSITORY

https://github.com/Graylog2/graylog2-server/pull/26055

Security Fix Commit FIX COMMIT

https://github.com/Graylog2/graylog2-server/commit/41d3745d0e52736d06c07d279ca0d72c1616df4c

Security Fix Commit FIX COMMIT

https://github.com/Graylog2/graylog2-server/commit/4f280138b53dc3bbb5749213e8cb1c8e372f23a2

Security Fix Commit FIX COMMIT

https://github.com/Graylog2/graylog2-server/commit/84b0ffa0bdf918f6edd2bb23a47254088634b1fc

Security Fix Commit FIX COMMIT

https://github.com/Graylog2/graylog2-server/commit/e5accc5f4ce48bd61b84bb8e5a13d21f8eac3da5

Graylog2 server Source Repository REPOSITORY

https://github.com/Graylog2/graylog2-server

Frequently Asked Questions

What is CVE-2026-55867?

CVE-2026-55867 is a security vulnerability in Graylog2 server involving Graylog token revocation endpoint allows authenticated users to delete other users’ access tokens under CWE-639: Authorization Bypass Through User-Controlled Key.

Which Graylog2 server versions are affected?

Affected versions include releases prior to 6.3.12, 7.0.7, 7.1.2 across affected packages: org.graylog2:graylog2-server.

What version fixes CVE-2026-55867?

Upgrading to 6.3.12, 7.0.7, 7.1.2 (or the latest patched release for your respective branch) resolves the vulnerability.

Is graylog2-server affected?

Yes, org.graylog2:graylog2-server is affected in releases prior to 6.3.12, 7.0.7, 7.1.2. Upgrade your dependency to 6.3.12, 7.0.7, 7.1.2 or later.

What CWE is associated with CVE-2026-55867?

CVE-2026-55867 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).

How can I check Maven dependencies for CVE-2026-55867?

Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.graylog2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

Machine-readable OSV JSON OSV v1.5 Schema

Normalized schema output

View Raw JSON

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j769-9gv9-65gr",
  "modified" : "2026-08-28T22:15:41Z",
  "published" : "2026-08-28T22:15:41Z",
  "aliases" : [ "CVE-2026-55867" ],
  "summary" : "Graylog token revocation endpoint allows authenticated users to delete other users’ access tokens",
  "details" : "### Impact\n\nGraylog contains an insecure direct object reference (IDOR) vulnerability in the token revocation endpoint. An authenticated user can delete access tokens belonging to other users, including service account tokens and administrator tokens, if they know or can guess a valid token identifier.\n\nThe issue does not expose token contents, but it allows unauthorized token deletion, leading to integrity impact and potential availability impact for access token based integrations.\n\n### Patches\n\nThe issue has been fixed in the following Graylog versions: `6.3.12`, `7.0.7`, `7.1.2`. Users should upgrade to one of these versions or above to remediate the vulnerability.\n\nGraylog Cloud has already been patched.\n\n### Workarounds\n\nThere are no feasible workarounds for this issue. Upgrading to a patched version is recommended.\n\nCustomers using Graylog Enterprise or Security can review the audit log[^1] for suspicious activity. Audit log lines for successful token deletions begin with `access token deleted from user`. \n\n### Credits\n\nThanks to [michaelddickenson](https://github.com/michaelddickenson) and [sreelim](https://github.com/sreelim) for reporting.\n\n\n[^1]: https://go2docs.graylog.org/current/interacting_with_your_log_data/audit_log.html",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"
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    },
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    "url" : "https://github.com/Graylog2/graylog2-server/pull/26053"
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    "nvd_published_at" : null
  }
}

CVSS V4

N/A MODERATE

Attack Vector N/A

Attack Complexity N/A

Privileges Required N/A

User Interaction N/A

Scope N/A

Confidentiality N/A

Integrity N/A

Availability N/A

Vector String

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

Advisory Metadata

Source ID: GHSA-j769-9gv9-65gr
Schema Version: 1.4.0
Published: 2026-08-28 22:15
Last Modified: 2026-08-28 22:15
Database Record File: advisories/github-reviewed/2026/08/GHSA-j769-9gv9-65gr/GHSA-j769-9gv9-65gr.json