CVE-2026-5466

/* * PoC Concept for CVE-2026-5466 * Demonstrates the lack of bounds checking on r and s in ECCSI verification. * This is a conceptual representation. */ #include <stdio.h> #include <string.h> #include <wolfssl/wolfcrypt/eccsi.h> // Mock structure for demonstration purposes int wc_VerifyEccsiHash_Mock(const byte* msg, word32 msgLen, const byte* id, word32 idLen, const byte* sig, word32 sigLen) { // In the vulnerable code, r and s are read without checking if they are in [1, q-1] // If we pass a signature where r=0, it might bypass checks if (sig[0] == 0) { // Hypothetical path where invalid signature is accepted return 0; // Success } return -1; // Failure } int main() { byte message[] = "Forged Message"; byte identity[] = "TargetIdentity"; // Crafted signature with r = 0 (invalid, but not checked in vulnerable version) byte forged_sig[64] = {0}; printf("Attempting to verify forged signature with r=0...\n"); int result = wc_VerifyEccsiHash_Mock(message, sizeof(message), identity, sizeof(identity), forged_sig, sizeof(forged_sig)); if (result == 0) { printf("[+] PoC Successful: Signature verified (Vulnerable behavior)\n"); } else { printf("[-] PoC Failed: Signature rejected\n"); } return 0; }

{"cve": {"id": "CVE-2026-5466", "sourceIdentifier": "[email protected]", "published": "2026-04-10T04:17:16.420", "lastModified": "2026-04-29T13:49:42.780", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "wolfSSL's ECCSI signature verifier `wc_VerifyEccsiHash` decodes the `r` and `s` scalars from the signature blob via `mp_read_unsigned_bin` with no check that they lie in `[1, q-1]`. A crafted forged signature could verify against any message for any identity, using only publicly-known constants."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/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": 7.6, "baseSeverity": "HIGH", "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "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:N/S:U/C:H/I:H/A:N", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-347"}]}], "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/10102", "source": "[email protected]", "tags": ["Issue Tracking"]}]}}