{"id":"CVE-2026-40944","aliases":["GHSA-7jrq-q4pq-rhm6","GO-2026-5226"],"url":"https://o3.security/vulnerability/CVE-2026-40944","summary":"Oxia: TLS CA certificate chain validation fails with multi-certificate PEM bundles","details":"### Summary\nThe `trustedCertPool()` function in the TLS configuration only parses the first PEM block from CA certificate files. When a CA bundle contains multiple certificates (e.g., intermediate + root CA), only the first certificate is loaded. This silently breaks certificate chain validation for mTLS.\n\n### Impact\nIn deployments using mTLS with certificate chains (intermediate CA + root CA bundles), legitimate clients with properly chained certificates are rejected with `x509: certificate signed by unknown authority`. This degrades the security posture by making mTLS unusable with standard CA chain configurations, potentially forcing operators to disable client certificate verification.\n\nAll versions using TLS with `trustedCaFile` configuration are affected.\n\n### Details\nIn `common/security/tls.go`, the `trustedCertPool()` method calls `pem.Decode()` only once, processing a single PEM block. The remaining bytes (containing additional certificates) are silently discarded. Additionally, the error return from `pem.Decode` is ignored, so a corrupted CA file results in an empty certificate pool without any error.\n\n### Patches\nFixed by iterating over all PEM blocks in the file, parsing each CERTIFICATE block, and returning an error if no valid certificates are found.\n\n### Workarounds\nUse CA files containing only a single certificate (the direct issuer of client certificates, not a chain).","published":"2026-04-21T21:14:56.814Z","modified":"2026-08-12T03:51:07.964338775Z","cvss":null,"epss":{"score":0.0016,"percentile":0.05403,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/oxia-db/oxia","fixedVersion":"0.16.2"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40944.json"},{"type":"ADVISORY","url":"https://github.com/oxia-db/oxia/security/advisories/GHSA-7jrq-q4pq-rhm6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40944"},{"type":"PACKAGE","url":"https://github.com/oxia-db/oxia"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:07.964338775Z"}}