Vulnerability details
CVE-2026-71303
Lemur: Incomplete fix for CVE-2026-55166 -- ACME authority update endpoint allows non-admin to replace `acme_url` with internal IP, bypassing allowlist
Official description
Lemur manages TLS certificate creation. Prior to 1.9.3, _validate_acme_url enforced ACME_DIRECTORY_HOST_ALLOWLIST when an authority was created, but PUT /api/1/authorities/ passed options to lemur/authorities/service.py without applying the same check. A user holding an authority role could replace the stored acme_url with an internal service or instance-metadata URL such as 169.254.169.254. The next issuance operation loaded that value and passed it to ClientV2.get_directory, causing an outbound request from the Lemur backend. This bypassed the creation-time mitigation for CVE-2026-55166 and could expose internal services or cloud metadata. The fix revalidates acme_url whenever authority options are updated. This issue is fixed in version 1.9.3.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.7High | 3.1 | CVEProject cvelistV5 (CNA) (GitHub_M) | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| Netflix | lemur | < 1.9.3 | CVEProject cvelistV5 (CNA) |
References and advisories
3- https://github.com/Netflix/lemur/commit/edca0390f930344d65ff4ca37a669c2320e3dfad x_refsource_MISC
- https://github.com/Netflix/lemur/releases/tag/v1.9.3 x_refsource_MISC
- https://github.com/Netflix/lemur/security/advisories/GHSA-v5rc-cpwc-cfpr x_refsource_CONFIRM
Details
- Published
- 2026-08-18
- Last updated
- 2026-08-18
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- Proof of concept
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-918Server-Side Request Forgery (SSRF)