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Not in CISA KEV
HIGH severity

CVE-2026-70666

HIGHFix: Netflix/lemur@6dcb19b

CVE-2026-70666 is a high-severity (CVSS 7.4) Server-Side Request Forgery (SSRF) vulnerability. O3 Security confirms whether CVE-2026-70666 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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…

Published
Aug 18, 2026
Updated
Aug 18, 2026
Affected
0 pkgs
Patched
None yet
Exploits
None indexed
Exploitation data as of Aug 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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.

Detection & mitigation playbook

Vulnerability
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Remediation status

    No patched version of the affected component has shipped for CVE-2026-70666 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-70666 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-70666. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 f
O3 Security · Impact-Aware SCA

Is CVE-2026-70666 in your dependencies?

O3 detects CVE-2026-70666 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.