Vulnerability in lemur (CVE-2026-55166)
Summary
Vulnerability in lemur (CVE-2026-55166). Confidential information can be exposed externally. Exploitable via POST /api/1/authorities. Mitigation: upgrade to 1.9.2 or later.
Original description
The description as published by the source.
Vulnerability Summary
| Field | Value |
|---|---|
| Title | Lemur 1.9.0: any SSO-authenticated user achieves AWS IAM compromise and permanent PKI key access via ACME acme_url SSRF and creator-equality IDOR |
| Component | lemur/lemur/plugins/lemur_acme/acme_handlers.py:161-201 (SSRF), lemur/lemur/certificates/views.py:734 (IDOR), lemur/lemur/auth/views.py:300-308 (SSO auto-provision) |
| CWE | CWE-918 (SSRF) + CWE-639 (Authorization Bypass Through User-Controlled Key) + CWE-285 (Improper Authorization) |
| Attack Prerequisite | A valid SSO session against the deployment's IdP. Lemur auto-provisions any new SSO identity at active=True, so an attacker with corporate SSO (or any federated IdP Lemur trusts) clears this bar. |
| Affected Versions | github.com/Netflix/lemur version = "1.9.0" (see lemur/lemur/about.py) and every prior release that carries the same three sinks. |
Executive Summary
A low-privilege user with a freshly-provisioned SSO account turns Lemur into an AWS IAM credential-exfiltration tool and walks away with a permanent copy of any TLS private key Lemur issued. Three sinks combine: (1) Lemur auto-creates every new SSO identity as active=True with no admin approval; (2) the ACME authority-creation endpoint accepts an attacker-supplied acme_url and fetches it server-side with no allowlist, reaching EC2 IMDS at 169.2…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-55166 has been found in lemur.
Attackers can target a specific entry point like POST /api/1/authorities over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.9/10.
What to do: upgrade lemur to 1.9.2 or later.
If unsure, ask your IT team or search "lemur CVE-2026-55166" on the vendor's site.
CVE-2026-55166 (lemur) — CWE-285 / CVSS v3 9.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/1/authorities / GET /latest/meta-data/iam/security-credentials/role / POST /api/1/certificates / GET /api/1/certificates/1/key
Patched: 1.9.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-285) exists in lemur. Attackers reach the vulnerable code path via POST /api/1/authorities.
Check the vendor advisory for the affected versions of lemur. Attack surface: POST /api/1/authorities / GET /latest/meta-data/iam/security-credentials/role / POST /api/1/certificates / GET /api/1/certificates/1/key.
Severity: Critical (CVSS 9.9/10). Confidential information can be exposed externally.
Update to 1.9.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/1/authorities requests with malformed payloads or SQL meta-characters. Run grep -r 'lemur' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'lemur' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
lemurを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/1/authorities' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/1/authoritiesへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade lemur to 1.9.2ステージング環境で 1.9.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against POST /api/1/authorities on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- package pypi.org
- web github.com
- web security-advisories@github.com
- web security-advisories@github.com