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.

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Source ID Title
Github GHSA Github GHSA GHSA-xpmj-wjcp-6pww Lemur: Server-Side Request Forgery via the ACME client following server-controlled URLs
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 18 Aug 2026 21:00:00 +0000

Type Values Removed Values Added
First Time appeared Netflix
Netflix lemur
Vendors & Products Netflix
Netflix lemur

Tue, 18 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Lemur: Server-Side Request Forgery via the ACME client following server-controlled URLs
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-18T19:05:26.621Z

Reserved: 2026-08-04T21:48:08.613Z

Link: CVE-2026-70666

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-18T20:17:23.237

Modified: 2026-08-18T20:17:23.237

Link: CVE-2026-70666

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-18T21:00:04Z

Weaknesses