CVE-2026-70666

Lemur manages TLS certificate creation. Prior to 1.9.3, an authority-role member could update acme_url through PUT /api/1/authorities/ without revalidation and direct setup_acme_client_no_retry to an attacker-controlled ACME server. ACME directory and order responses contain newNonce, newOrder, authorizations, and finalize URLs chosen by that server. The Lemur ClientV2 followed those URLs without requiring their host to match the configured directory host, allowing JWS-signed requests to internal services or cloud metadata endpoints. The issue required an ACME authority and a user authorized for that authority, but did not require global administrator privileges. The fix revalidates updates and introduces _PinnedClientNetwork to enforce a single allowed host for the complete ACME flow. This issue is fixed in version 1.9.3.

CVSS 3.1

7.4CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

EPSS

0.2% chance of exploitation in the next 30 days; higher than 11% of CVEs (scores of 2026-10-25)

CWE

CWE-918

Published

2026-08-18

Modified

2026-10-22

Record from

the NVD, synced 2026-10-23

Packages (OSV)

References

• https://github.com/Netflix/lemur/commit/6dcb19b6d6004e97796d6a0344b130b2ba57f050
• https://github.com/Netflix/lemur/releases/tag/v1.9.3
• https://github.com/Netflix/lemur/security/advisories/GHSA-xpmj-wjcp-6pww

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