CVE-2026-55163
Received Received - Intake

Role Permission Escalation in Lemur

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: GitHub, Inc.

Description
Lemur manages TLS certificate creation. Prior to 1.9.2, PUT /api/1/roles/ in lemur/roles/views.py:298 authorized updates with RoleMemberPermission(role_id), which allowed either an administrator or any existing member of the target role. The handler passed data["users"] and data["name"] to service.update, allowing a non-admin member to add or remove other users and rename the role. This enabled lateral privilege grants within roles that control certificate and authority access and could deny access by removing legitimate members. The DELETE handler already required admin_permission, confirming that the weaker PUT authorization was inconsistent. The fix applies the same administrator-only requirement to the PUT handler. This issue is fixed in version 1.9.2.

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Meta Information

Published
2026-08-18
Last Modified
2026-08-18
Generated
2026-08-18
AI Q&A
2026-08-18
EPSS Evaluated
N/A
NVD
CVE-2026-55163
EUVD
EUVD-2026-61147

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
lemur lemur 1.9.2

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

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Executive Summary

CVE-2026-55163 is a privilege escalation flaw in Lemur software versions before 1.9.2. It allows non-admin role members to modify role memberships via the PUT /api/1/roles/<id> endpoint. The vulnerability stems from improper authorization checks that only verify role membership instead of requiring admin privileges.

Detection Guidance

To detect this vulnerability, check if your Lemur instance is running a version prior to 1.9.2. Use the command: curl -s https://<lemur-server>/api/1/roles/ | grep version. If the version is <=1.9.1, the system is vulnerable. Additionally, monitor logs for unauthorized PUT requests to /api/1/roles/<id> by non-admin users.

Impact Analysis

An attacker with basic role membership could add or remove users, rename roles, or modify descriptions. This could grant unauthorized access to certificate and authority controls, enable lateral privilege movement, or disrupt governance by removing legitimate members.

Compliance Impact

This vulnerability could violate compliance requirements by enabling unauthorized access to sensitive systems or data. It undermines role-based access controls and audit trails, which are critical for GDPR and HIPAA compliance.

Mitigation Strategies

Immediately upgrade Lemur to version 1.9.2 or later. If upgrading is not possible, restrict access to the PUT /api/1/roles/<id> endpoint to administrators only by modifying the authorization logic in lemur/roles/views.py to enforce admin_permission.require for PUT requests.

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