Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-71308Lemur: Unchecked `replaces[]` lets any user silence notifications and hijack auto-rotation for arbitrary certificates
High 8.1
In plain English
A high-severity authorization bypass via user-controlled key in lemur from Netflix. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Lemur manages TLS certificate creation. From 0.5.0 until 1.9.3, certificate create, upload, and edit requests accepted replaces[] or replacements identifiers that AssociatedCertificateSchema resolved with fetch_objects without a CertificatePermission check. Assigning those objects to Certificate.replaces invoked an append listener that disabled the victim certificate notifications and marked it as replaced. The victim was then excluded from get_all_pending_reissue, and certificate_rotate could deploy the attacker certificate to endpoints serving the victim. An authenticated non-read-only user could target certificates for which the user had no ownership or role, suppress lifecycle automation, and cause fleet-wide TLS disruption or unauthorized substitution. The fix authorizes every referenced replacement certificate before mutation. This issue is fixed in version 1.9.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | lemur | 1.9.3 | GHSA-cfh6-pv5c-38jv |
| PyPI | lemur | 1.9.3 | PYSEC-2026-3675 |
Affected products (as reported)
Weakness: CWE-639, CWE-862 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
References
- https://github.com/Netflix/lemur/security/advisories/GHSA-cfh6-pv5c-38jv x_refsource_CONFIRM
- https://github.com/Netflix/lemur/commit/286874535160952143b0afe2d356642669f9d4c6 x_refsource_MISC
- https://github.com/Netflix/lemur/releases/tag/v1.9.3 x_refsource_MISC