{"id":"CVE-2026-5501","summary":"Improper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates","details":"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.","modified":"2026-07-16T03:48:42.266618826Z","published":"2026-04-10T03:07:39.604Z","database_specific":{"cwe_ids":["CWE-295"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5501.json","cna_assigner":"wolfSSL"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5501.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-5501"},{"type":"FIX","url":"https://github.com/wolfSSL/wolfssl/pull/10102"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/wolfssl/wolfssl","events":[{"introduced":"0"},{"last_affected":"922d04b3568c6428a9fb905ddee3ef5a68db3108"}],"database_specific":{"cpe":"cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"last_affected":"5.9.0"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v5.9.0-stable","v5.8.4-stable","wolfEntropy2d","v5.8.2-stable","wolfEntropy1","v5.8.0-stable","v5.7.6-stable","v5.7.4-stable","v5.2.1","v5.7.2-stable","v5.7.0-stable","v5.6.6-stable","v5.6.4-stable","WCv5.0-RC12","WCv5.0-RC11","WCv5.0-RC10","v5.6.2-stable","v5.6.3-stable","v5.6.0-stable","v5.5.4-stable","v5.5.3-stable","v5.5.2-stable","v5.5.1-stable","v5.5.0-stable","v5.4.0-stable","v5.3.0-stable","v5.2.0-stable","v5.1.0-stable","v5.0.0-stable","WCv5.0-RC9","v4.8.0-stable","v4.7.1r","v4.7.0-stable","v4.6.0-stable","v4.5.0-stable","v4.4.0-stable","v4.3.0-stable","v4.2.0c","v4.2.0-stable","v4.1.0-stable","v4.0.0-stable","list","v3.15.7-stable","v3.15.6","v3.15.5a","v3.15.5-stable","WCv4-rng-stable","v3.15.3-stable","l","v3.15.0-stable","v3.14.4","v3.14.2","v3.14.0b","v3.14.0a","v3.14.0-stable","v3.13.3","v3.13.2","v3.13.0-stable","v3.12.2-stable","v3.12.0-stable","v3.11.1-tls13-beta","v3.11.0-stable","v3.10.3","v3.10.2-stable","v3.10.0a","v3.10.0-stable","v3.9.10b","v3.9.10-stable","v3.9.8","v3.9.6w","v3.9.6","v3.9.1","v3.9.0","v3.8.0","v3.7.3","v3.7.1","v3.7.0","v3.6.9","v3.6.8","v3.4.6","v3.4.2","v3.4.0","v3.3.3","v3.3.0","v3.2.6","v3.2.4","v3.2.0","v2.9.4","v2.9.2","v2.9.1","v0.5","v2.9.0","v2.8.6","v2.8.5a","v2.8.5","v2.8.4","v2.8.3","v2.8.2","v2.8.0","v2.7.2","v2.7.0","v2.6.2","v2.6.0","v2.4.7","v2.4.6","v2.4.2","v2.0.8","v2.0.6","v2.0.3","v2.0.2","v2.0rc3","v2.0rc2b","v2.0rc2","v2.0rc1","v1.9.0","v1.8.8.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5501.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}