{"id":"CVE-2026-54291","aliases":["BIT-postgresql-jdbc-driver-2026-54291","GHSA-j92g-9f8w-j867"],"url":"https://o3.security/vulnerability/CVE-2026-54291","summary":"Silent channel-binding authentication downgrade via unsupported certificate algorithms","details":"### Impact\n\n`channelBinding=require` connections can be silently downgraded from `SCRAM-SHA-256-PLUS` (with channel binding) to plain `SCRAM-SHA-256` (without it), losing the man-in-the-middle protection the setting is meant to guarantee. An attacker who can intercept the TLS connection triggers the downgrade with a certificate whose signature algorithm has no `tls-server-end-point` channel-binding hash. Examples are `Ed25519`, `Ed448`, and post-quantum algorithms.\n\nTwo issues combine in releases 42.7.4 through 42.7.11:\n\n1. The bundled `com.ongres.scram:scram-client` (3.1 or 3.2) returns an empty byte array instead of failing when it cannot derive the binding hash for such a certificate. This is the library issue tracked as [GHSA-p9jg-fcr6-3mhf](https://github.com/ongres/scram/security/advisories/GHSA-p9jg-fcr6-3mhf).\n2. pgJDBC does not enforce `channelBinding=require` where it matters. `ScramAuthenticator` checks only that the server *advertised* a `-PLUS` mechanism; it neither rejects the empty binding nor checks that the *negotiated* mechanism uses channel binding. The connection therefore downgrades silently, and would do so even against a fixed `scram-client`, because the missing enforcement is in pgJDBC's own code.\n\nOnly connections that set `channelBinding=require` are affected. Under the default `prefer` policy, and under `allow` or `disable`, falling back to plain SCRAM is the documented behaviour. Releases before 42.7.4 are unaffected, because they do not support channel binding.\n\n### Patches\n\nFixed in pgJDBC 42.7.12. pgJDBC now enforces channel binding in its own code, independently of the `scram-client` version:\n\n- Under `channelBinding=require`, it fails the connection when no channel-binding data can be extracted from the server certificate, instead of passing an empty value to the SCRAM client. The error names the certificate signature algorithm.\n- After negotiation, it requires the selected mechanism to use channel binding (a `-PLUS` mechanism) whenever `channelBinding=require` is set, regardless of how negotiation resolved.\n\nUpgrade to 42.7.12 or later.\n\n### Workarounds\n\nNo pgJDBC setting restores channel-binding enforcement on an affected release; upgrading is the fix.\n\nIf you cannot upgrade immediately, verify the server certificate at the TLS layer so that a man-in-the-middle cannot present a substitute certificate. Set `sslmode=verify-full` with a truststore that contains only your server's CA. This defence is independent of channel binding and blocks the same attacker. Connections that rely on `channelBinding=require` in place of certificate verification have no equivalent workaround and should upgrade.\n\n### References\n\n-  [GHSA-p9jg-fcr6-3mhf](https://github.com/ongres/scram/security/advisories/GHSA-p9jg-fcr6-3mhf) — the related `com.ongres.scram:scram-client` issue (root cause of the empty channel-binding value).\n- `scram-client` 3.3 release (library fix): https://github.com/ongres/scram/releases/tag/3.3\n- pgJDBC fix in 42.7.12: [commit](https://github.com/pgjdbc/pgjdbc/commit/77df98e4e66c12936ded3478a0954f6f580bad99)","published":"2026-07-06T18:55:01.675Z","modified":"2026-10-21T10:17:36.661032006Z","cvss":null,"epss":{"score":0.00236,"percentile":0.14839,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Maven","name":"org.postgresql:postgresql","fixedVersion":"42.7.12"}],"fix":{"url":"https://github.com/pgjdbc/pgjdbc/commit/77df98e4e66c12936ded3478a0954f6f580bad99","label":"pgjdbc/pgjdbc@77df98e"},"references":[{"type":"WEB","url":"https://github.com/ongres/scram/releases/tag/3.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54291.json"},{"type":"ADVISORY","url":"https://github.com/pgjdbc/pgjdbc/security/advisories/GHSA-j92g-9f8w-j867"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54291"},{"type":"FIX","url":"https://github.com/pgjdbc/pgjdbc/commit/77df98e4e66c12936ded3478a0954f6f580bad99"},{"type":"PACKAGE","url":"https://github.com/pgjdbc/pgjdbc"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T10:17:36.661032006Z"}}