Vulnerability in lemur (CVE-2026-44304)
Summary
Vulnerability in lemur (CVE-2026-44304). Confidential information can be exposed externally. Exploitable via POST /auth/login. Mitigation: upgrade to 1.9.0 or later.
Original description
The description as published by the source.
Description
Overview
Lemur's LDAP authentication module (lemur/auth/ldap.py) constructs LDAP search filters using unsanitized user input via Python string interpolation. An authenticated LDAP user can inject LDAP filter metacharacters through the username field to manipulate group membership queries and escalate their privileges to administrator.
Vulnerable Code
Location: lemur/auth/ldap.py, _bind() method
Filter 1 — User lookup (line ~161):
ldap_filter = "userPrincipalName=%s" % self.ldap_principal
self.ldap_principal is derived directly from args["username"] submitted at POST /auth/login with no sanitization. The ldap.filter.escape_filter_chars() function is never called.
Filter 2 — Active Directory group lookup (line ~189):
groupfilter = "(&(objectclass=group)(member:1.2.840.113556.1.4.1941:={}))".format(userdn)
The userdn value is derived from the LDAP response to the first unsanitized query, making it potentially tainted as well.
Impact
An authenticated LDAP user can:
- Inject LDAP filter syntax into the username field during login
- Manipulate the group membership query to return arbitrary groups
- Be assigned the
adminrole or any other privileged role in Lemur - Gain unauthorized access to all certificates, private keys (via
/certificates//key), and CA configurations - Issue certificates under any authority
Exploitation Constraint
The simple_bind_s() call must succeed be…
Source: NIST National Vulnerability Database 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-2026-44304 has been found in lemur.
Attackers can target a specific entry point like POST /auth/login over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade lemur to 1.9.0 or later.
If unsure, ask your IT team or search "lemur CVE-2026-44304" on the vendor's site.
CVE-2026-44304 (lemur) — CWE-90 / CVSS v3 8.1
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /auth/login / self.ldap_principal / userdn / admin
Patched: 1.9.0 — 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-90) exists in lemur. Attackers reach the vulnerable code path via POST /auth/login.
Check the vendor advisory for the affected versions of lemur. Attack surface: POST /auth/login / self.ldap_principal / userdn / admin.
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.
Update to 1.9.0.
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 /auth/login 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 /auth/login' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /auth/login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 1.9.0ステージング環境で 1.9.0 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 /auth/login 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 nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com