Improper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates_CVE-2026-5501

{
    "lastseen": "",
    "description": "wolfSSL_X509_verify_cert in the OpenSSL compatibility layer accepts a certificate chain in which the leaf's signature is not checked, if the attacker supplies an untrusted intermediate with Basic Constraints `CA:FALSE` that is legitimately signed by a trusted root. An attacker who obtains any leaf certificate from a trusted CA (e.g. a free DV cert from Let's Encrypt) can forge a certificate for any subject name with any public key and arbitrary signature bytes, and the function returns `WOLFSSL_SUCCESS` / `X509_V_OK`. The native wolfSSL TLS handshake path (`ProcessPeerCerts`) is not susceptible and the issue is limited to applications using the OpenSSL compatibility API directly, which would include integrations of wolfSSL into nginx and haproxy.",
    "published": "2026-04-10T03:07:39.604Z",
    "modified": "2026-04-10T13:43:04.704Z",
    "type": "cve",
    "title": "Improper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates",
    "source": "wolfSSL",
    "references": "https://github.com/wolfSSL/wolfssl/pull/10102",
    "id": "CVE-2026-5501",
    "bulletinFamily": "",
    "cwe": [
        "CWE-295"
    ],
    "cvelist": null,
    "sourceData": "wolfSSL wolfSSL 0",
    "sourceHref": "",
    "cvss": {
        "score": 8.6,
        "severity": "HIGH",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "wolfSSL",
    "version": "0",
    "vendor": "wolfSSL",
    "ai_description": "Improper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates",
    "ai_severity": "High",
    "ai_vendor": "wolfSSL",
    "ai_product": "wolfSSL",
    "ai_version": "0",
    "ai_score": 8.6
}