CVE-2026-71417
Received Received - Intake

Lemur TLS Certificate Revocation Bypass Vulnerability

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: GitHub, Inc.

Description
Lemur manages TLS certificate creation. Prior to 1.9.3, POST /api/1/certificates/upload allowed a non-read-only user to create a duplicate row using another certificate body, authority_id, serial, or external_id without requiring permission on the underlying authority. PUT /api/1/certificates//revoke authorized the caller against only the selected Lemur row, so the creator of the duplicate bypassed CertificatePermission. The duplicate had no cert.endpoints, which also bypassed the safeguard that prevents revocation of deployed certificates. Issuer plugins then revoked the real CA-side certificate using certificate.body or external_id under the stored authority credentials. An attacker could therefore revoke arbitrary managed certificates and cause fleet-wide TLS denial of service. The fix rejects duplicate authority_id and serial identities, requires authority access on upload, and checks every matching row during revocation. This issue is fixed in version 1.9.3.

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Meta Information

Published
2026-08-18
Last Modified
2026-08-18
Generated
2026-08-19
AI Q&A
2026-08-18
EPSS Evaluated
N/A
NVD
CVE-2026-71417
EUVD
EUVD-2026-61161

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
lemur lemur 1.9.3
netflix lemur 1.9.3
netflix lemur to 1.9.3 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-639 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.

Attack-Flow Graph

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Executive Summary

This vulnerability in Lemur before version 1.9.3 allows non-read-only users to create duplicate certificate entries by reusing fields like certificate body, authority ID, serial, or external ID without proper authority permissions. The PUT endpoint for revoking certificates only checks the selected row, so attackers could bypass CertificatePermission controls. The duplicate entries lack certificate endpoints, bypassing safeguards that prevent revocation of deployed certificates. This enables attackers to revoke arbitrary managed certificates, causing fleet-wide TLS denial of service.

Detection Guidance

Check Lemur logs for unauthorized certificate uploads or revocations. Look for duplicate entries in the database for authority_id, serial, or external_id. Verify that only authorized users have access to POST /api/1/certificates/upload and PUT /api/1/certificates//revoke endpoints.

Impact Analysis

If exploited, this vulnerability could allow an attacker to revoke critical TLS certificates across your infrastructure, leading to widespread service disruptions. Systems relying on these certificates would fail to establish secure connections, causing downtime for applications, APIs, or services using Lemur-managed certificates. The impact includes potential loss of data integrity and availability for encrypted communications.

Compliance Impact

This vulnerability could lead to non-compliance with GDPR and HIPAA by disrupting encrypted communications, potentially exposing sensitive data. GDPR requires protection of personal data, and HIPAA mandates secure transmission of health information. Revoked certificates may cause unauthorized access or data breaches, violating these regulations and resulting in legal penalties or loss of trust.

Mitigation Strategies

Upgrade Lemur to version 1.9.3 or later. Restrict access to certificate management endpoints to authorized users only. Review and remove any duplicate certificate entries in the database. Monitor for unauthorized revocations or certificate modifications.

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