{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "lemur"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44305"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-06T18:48:12Z",
    "nvd_published_at": "2026-05-12T22:16:37Z",
    "severity": "MODERATE"
  },
  "details": "## Description\n\n### Overview\n\nWhen LDAP TLS is enabled (`LDAP_USE_TLS = True`), Lemur\u0027s LDAP authentication module unconditionally disables TLS certificate verification at the **global** `ldap` module level. This allows a man-in-the-middle attacker positioned between Lemur and the LDAP server to intercept all authentication credentials.\n\n### Vulnerable Code\n\n**Location:** `lemur/auth/ldap.py`, `_bind()` method, line ~172\n\n```python\nif self.ldap_use_tls:\n    ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)\n```\n\nKey issues:\n\n1. `ldap.set_option()` is a **global** call (as opposed to `self.ldap_client.set_option()`), meaning it disables TLS verification for the entire Python process, not just this connection\n2. `OPT_X_TLS_NEVER` means no certificate validation is performed whatsoever \u2014 self-signed, expired, wrong hostname, and revoked certificates are all silently accepted\n3. There is no configuration option to override this behavior \u2014 TLS verification is always disabled when TLS is enabled\n\n### Impact\n\nA network-positioned attacker (man-in-the-middle) between Lemur and the LDAP server can:\n\n- **Intercept all LDAP credentials** (usernames and plaintext passwords) for every user who authenticates\n- **Modify LDAP responses** to inject arbitrary group memberships, granting admin access\n- **Compromise the entire PKI infrastructure** managed by Lemur, since authentication controls access to certificates and private keys\n\nThis is particularly severe because Lemur is a certificate management system \u2014 the tool designed to manage TLS security is itself vulnerable to a TLS attack.\n\n### Steps to Reproduce\n\n1. Deploy Lemur with LDAP TLS enabled:\n   ```python\n   LDAP_AUTH = True\n   LDAP_USE_TLS = True\n   LDAP_BIND_URI = \"ldaps://dc.corp.example.com\"\n   ```\n\n2. Intercept the LDAP connection using a TLS proxy (e.g., `mitmproxy` or `stunnel`):\n   ```bash\n   # Generate a self-signed certificate\n   openssl req -x509 -newkey rsa:2048 -keyout mitm.key -out mitm.crt -days 1 -nodes -subj \"/CN=mitm\"\n\n   # Proxy LDAP traffic\n   stunnel -d 0.0.0.0:636 -r real-ldap-server:636 -p mitm.pem\n   ```\n\n3. Point Lemur\u0027s `LDAP_BIND_URI` at the proxy (or perform ARP spoofing/DNS hijacking)\n\n4. Observe that Lemur connects without any certificate verification error\n\n5. All credentials are visible in the proxy\u0027s TLS session\n\n### Remediation\n\nRemove the global TLS verification bypass and default to strict verification:\n\n```python\nif self.ldap_use_tls:\n    # Use instance-level option, not global\n    self.ldap_client.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_DEMAND)\n    self.ldap_client.set_option(ldap.OPT_PROTOCOL_VERSION, 3)\n    if self.ldap_cacert_file:\n        self.ldap_client.set_option(ldap.OPT_X_TLS_CACERTFILE, self.ldap_cacert_file)\n```\n\nIf backward compatibility is needed, make it configurable with a secure default:\n\n```python\ntls_require_cert = current_app.config.get(\"LDAP_TLS_REQUIRE_CERT\", ldap.OPT_X_TLS_DEMAND)\nself.ldap_client.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, tls_require_cert)\n```\n\n### Resources\n\n- CWE-295: https://cwe.mitre.org/data/definitions/295.html\n- python-ldap TLS documentation: https://www.python-ldap.org/en/python-ldap-3.4.0/reference/ldap.html#tls-options",
  "id": "GHSA-vr7c-r5gj-j3w5",
  "modified": "2026-05-13T16:41:37Z",
  "published": "2026-05-06T18:48:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Netflix/lemur/security/advisories/GHSA-vr7c-r5gj-j3w5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44305"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Netflix/lemur"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Netflix/lemur/releases/tag/v1.9.0"
    },
    {
      "type": "WEB",
      "url": "https://www.python-ldap.org/en/python-ldap-3.4.0/reference/ldap.html#tls-options"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Lemur: LDAP Authentication Globally Disables TLS Certificate Verification When LDAP_USE_TLS Is Enabled"
}