Vulnerability-Lookup

CVE-2026-44304 (GCVE-0-2026-44304)

Vulnerability from cvelistv5 – Published: 2026-05-12 21:27 – Updated: 2026-05-14 12:33

Title

Lemur: LDAP Filter Injection enables post-authentication privilege escalation

Summary

Lemur manages TLS certificate creation. Prior to 1.9.0, 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. This vulnerability is fixed in 1.9.0.

Severity

8.1 (High)


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

CWE

CWE-90 - Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/Netflix/lemur/security/advisor…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
Netflix	lemur	Affected: < 1.9.0

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44304

Vulnerability from fkie_nvd - Published: 2026-05-12 22:16 - Updated: 2026-05-14 13:16

Severity

8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/Netflix/lemur/security/advisories/GHSA-3r34-vq8m-39gh
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/Netflix/lemur/security/advisories/GHSA-3r34-vq8m-39gh

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
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    {
      "lang": "en",
      "value": "Lemur manages TLS certificate creation. Prior to 1.9.0, Lemur\u0027s 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. This vulnerability is fixed in 1.9.0."
    }
  ],
  "id": "CVE-2026-44304",
  "lastModified": "2026-05-14T13:16:19.473",
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    }
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GHSA-3R34-VQ8M-39GH

Vulnerability from github – Published: 2026-05-06 19:16 – Updated: 2026-05-13 16:41

Summary

Lemur: LDAP Filter Injection enables post-authentication privilege escalation

Details

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 admin role or any other privileged role in Lemur
Gain unauthorized access to all certificates, private keys (via /certificates/<id>/key), and CA configurations
Issue certificates under any authority

Exploitation Constraint

The simple_bind_s() call must succeed before the injectable filter is reached, so the attacker requires valid LDAP credentials. This is a post-authentication privilege escalation.

Steps to Reproduce

Deploy Lemur with LDAP authentication enabled: python LDAP_AUTH = True LDAP_IS_ACTIVE_DIRECTORY = True LDAP_BIND_URI = "ldaps://dc.corp.example.com" LDAP_BASE_DN = "DC=corp,DC=example,DC=com" LDAP_EMAIL_DOMAIN = "corp.example.com"
Create a valid LDAP user account
Send login request with crafted username containing LDAP metacharacters: ``` POST /auth/login Content-Type: application/json

{ "username": "validuser)(memberOf=CN=LemurAdmins,DC=corp,DC=example,DC=com", "password": "validpassword" } 4. The LDAP filter becomes: userPrincipalName=validuser)(memberOf=CN=LemurAdmins,DC=corp,DC=example,DC=com@corp.example.com ``` 5. Depending on the LDAP server's parsing, this can alter query semantics 6. The user is assigned roles they should not have access to

Remediation

Apply ldap.filter.escape_filter_chars() to all user-controlled values before interpolation:

from ldap.filter import escape_filter_chars

# Fix 1: User lookup filter
ldap_filter = "userPrincipalName=%s" % escape_filter_chars(self.ldap_principal)

# Fix 2: Active Directory group filter
groupfilter = "(&(objectclass=group)(member:1.2.840.113556.1.4.1941:={}))".format(
    escape_filter_chars(userdn)
)

Resources

CWE-90: https://cwe.mitre.org/data/definitions/90.html
OWASP LDAP Injection: https://owasp.org/www-community/attacks/LDAP_Injection
Python ldap.filter.escape_filter_chars: https://www.python-ldap.org/en/python-ldap-3.4.0/reference/ldap-filter.html

Severity

8.1 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "lemur"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44304"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-90"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-06T19:16:59Z",
    "nvd_published_at": "2026-05-12T22:16:37Z",
    "severity": "HIGH"
  },
  "details": "## Description\n\n### Overview\n\nLemur\u0027s 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.\n\n### Vulnerable Code\n\n**Location:** `lemur/auth/ldap.py`, `_bind()` method\n\n**Filter 1 \u2014 User lookup (line ~161):**\n```python\nldap_filter = \"userPrincipalName=%s\" % self.ldap_principal\n```\n\n`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.\n\n**Filter 2 \u2014 Active Directory group lookup (line ~189):**\n```python\ngroupfilter = \"(\u0026(objectclass=group)(member:1.2.840.113556.1.4.1941:={}))\".format(userdn)\n```\n\nThe `userdn` value is derived from the LDAP response to the first unsanitized query, making it potentially tainted as well.\n\n### Impact\n\nAn authenticated LDAP user can:\n\n1. Inject LDAP filter syntax into the username field during login\n2. Manipulate the group membership query to return arbitrary groups\n3. Be assigned the `admin` role or any other privileged role in Lemur\n4. Gain unauthorized access to all certificates, private keys (via `/certificates/\u003cid\u003e/key`), and CA configurations\n5. Issue certificates under any authority\n\n### Exploitation Constraint\n\nThe `simple_bind_s()` call must succeed before the injectable filter is reached, so the attacker requires valid LDAP credentials. This is a **post-authentication privilege escalation**.\n\n### Steps to Reproduce\n\n1. Deploy Lemur with LDAP authentication enabled:\n   ```python\n   LDAP_AUTH = True\n   LDAP_IS_ACTIVE_DIRECTORY = True\n   LDAP_BIND_URI = \"ldaps://dc.corp.example.com\"\n   LDAP_BASE_DN = \"DC=corp,DC=example,DC=com\"\n   LDAP_EMAIL_DOMAIN = \"corp.example.com\"\n   ```\n2. Create a valid LDAP user account\n3. Send login request with crafted username containing LDAP metacharacters:\n   ```\n   POST /auth/login\n   Content-Type: application/json\n\n   {\n     \"username\": \"validuser)(memberOf=CN=LemurAdmins,DC=corp,DC=example,DC=com\",\n     \"password\": \"validpassword\"\n   }\n   ```\n4. The LDAP filter becomes:\n   ```\n   userPrincipalName=validuser)(memberOf=CN=LemurAdmins,DC=corp,DC=example,DC=com@corp.example.com\n   ```\n5. Depending on the LDAP server\u0027s parsing, this can alter query semantics\n6. The user is assigned roles they should not have access to\n\n### Remediation\n\nApply `ldap.filter.escape_filter_chars()` to all user-controlled values before interpolation:\n\n```python\nfrom ldap.filter import escape_filter_chars\n\n# Fix 1: User lookup filter\nldap_filter = \"userPrincipalName=%s\" % escape_filter_chars(self.ldap_principal)\n\n# Fix 2: Active Directory group filter\ngroupfilter = \"(\u0026(objectclass=group)(member:1.2.840.113556.1.4.1941:={}))\".format(\n    escape_filter_chars(userdn)\n)\n```\n\n### Resources\n\n- CWE-90: https://cwe.mitre.org/data/definitions/90.html\n- OWASP LDAP Injection: https://owasp.org/www-community/attacks/LDAP_Injection\n- Python ldap.filter.escape_filter_chars: https://www.python-ldap.org/en/python-ldap-3.4.0/reference/ldap-filter.html",
  "id": "GHSA-3r34-vq8m-39gh",
  "modified": "2026-05-13T16:41:43Z",
  "published": "2026-05-06T19:16:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Netflix/lemur/security/advisories/GHSA-3r34-vq8m-39gh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44304"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Netflix/lemur"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Netflix/lemur/releases/tag/v1.9.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Lemur: LDAP Filter Injection enables post-authentication privilege escalation"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-44304 (GCVE-0-2026-44304)

FKIE_CVE-2026-44304

GHSA-3R34-VQ8M-39GH

Description

Overview

Vulnerable Code

Impact

Exploitation Constraint

Steps to Reproduce

Remediation

Resources

Tags

Sightings

Nomenclature