CVE-2026-71303Lemur: Incomplete fix for CVE-2026-55166 -- ACME authority update endpoint allows non-admin to replace `acme_url` with internal IP, bypassing allowlist
- 7.7HighCVSS base score
- 0.28%Exploitation in 30 daysEPSS · top 80% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://github.com/Netflix/lemur/security/advisories/GHSA-v5rc-cpwc-cfpr (opens in a new tab)x_refsource_CONFIRMexploit
Timeline
ID reserved
By GitHub_M
- 13 days later
· 13 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
| NVDNVD · Deferred | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.28% · top 80% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.7.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
References
References3
- https://github.com/Netflix/lemur/security/advisories/GHSA-v5rc-cpwc-cfpr (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/Netflix/lemur/commit/edca0390f930344d65ff4ca37a669c2320e3dfad (opens in a new tab)x_refsource_MISC
- https://github.com/Netflix/lemur/releases/tag/v1.9.3 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-61154 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-v5rc-cpwc-cfpr (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-71303)Record last updated .