Lemur: Unchecked replaces[] lets any user silence notifications and hijack auto-rotation for arbitrary certificates

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS

• CVE-2026-71308: 0.32% estimated exploitation activity in the next 30 days; percentile 24.69 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Repo under test: https://github.com/Netflix/lemur The certificate create and upload endpoints accept a replaces[] (alias replacements) array that is resolved to live Certificate ORM objects with no ownership or CertificatePermission check on the referenced certificates. The SQLAlchemy Certificate.replaces append listener then immediately sets victim.notify = False and populates victim.replaced. From that point the victim certificate is excluded from auto-reissue, its expiration notifications are silenced, and the periodic certificaterotate Celery task deploys the attacker's certificate (endpoint.certificate.replaced[0]) onto every endpoint serving the victim certificate. Any authenticated non-read-only user can therefore silently substitute their own certificate onto production load balancers and Kubernetes secrets they hold no role on, while suppressing the legitimate certificate's lifecycle automation. Affected route POST /api/1/certificates POST /api/1/certificates/upload…

Published by the source

18 Aug 2026, 20:51 UTC

Last modified by the source

18 Aug 2026, 20:51 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cfh6-pv5c-38jv

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# Patch Next advisory brief: CVE-2026-71308

Advisory: Lemur: Unchecked `replaces[]` lets any user silence notifications and hijack auto-rotation for arbitrary certificates
IDs: CVE-2026-71308, GHSA-cfh6-pv5c-38jv
Record: https://patchnext.com/advisories/cve-2026-71308 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: lemur 1.9.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI lemur: affected >= 0.5.0, <= 1.9.2; fixed in 1.9.3

## Suggested inspection (read-only)
- `python -m pip show lemur`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on lemur.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cfh6-pv5c-38jv (GitHub-reviewed advisory GHSA-cfh6-pv5c-38jv lists affected ranges: PyPI lemur >=0.5.0 <=1.9.2)

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