CVE-2026-71303: high-severity vulnerability in Netflix lemur
Lemur: Incomplete fix for CVE-2026-55166 -- ACME authority update endpoint allows non-admin to replace `acme_url` with internal IP, bypassing allowlist
Published
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.7epss 0.3%
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:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Affected products
Netflix · lemurRelated CVEs — Netflix lemur
In the same product, most dangerous first.
CVE-2026-48508HIGHLemur: Authorization bypass in StrictRolePermission / AuthorityCreatorPermissionEPSS 0.3%CVE-2026-71308HIGHLemur: Unchecked `replaces[]` lets any user silence notifications and hijack auto-rotation for arbitrary certificatesEPSS 0.3%CVE-2026-71307HIGHLemur: Authenticated low-privilege users can read plaintext destination credentials (SFTP password / private-key passphrase) via the destinations APIEPSS 0.3%CVE-2026-55164MEDIUMLemur: Plaintext password storage in Lemur user-update pathEPSS 0.3%CVE-2026-55166CRITICALLemur: any SSO-authenticated user achieves AWS IAM compromise and permanent PKI key access via ACME acme_url SSRF and creator-equality IDOREPSS 0.3%CVE-2026-71322MEDIUMLemur: Missing authorization check on POST /certificates/<id>/export for plugins with requires_key = FalseEPSS 0.2%