Lemur: Server-Side Request Forgery via the ACME client following server-controlled URLs

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Summary

CVECVE-2026-70666
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 20:17:23 UTC
Updated2026-08-19 19:17:23 UTC
DescriptionLemur 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.

Risk And Classification

Primary CVSS: v3.1 7.4 HIGH from [email protected]

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

EPSS: 0.001650000 probability, percentile 0.061880000 (date 2026-08-19)

Problem Types: CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.4HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
3.1CNADECLARED7.4HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
Low

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Netflix Lemur affected < 1.9.3 Not specified

References

ReferenceSourceLinkTags
github.com/Netflix/lemur/security/advisories/GHSA-xpmj-wjcp-6pww [email protected] github.com
github.com/Netflix/lemur/releases/tag/v1.9.3 [email protected] github.com
github.com/Netflix/lemur/commit/6dcb19b6d6004e97796d6a0344b130b2ba57f050 [email protected] github.com
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