CVE-2026-54291: PostgreSQL JDBC Driver Silent Channel-binding Authentication Downgrade Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j92g-9f8w-j867",
  "modified" : "2026-07-21T17:47:39Z",
  "published" : "2026-07-21T17:47:39Z",
  "aliases" : [ "CVE-2026-54291" ],
  "summary" : "PostgreSQL JDBC Driver: 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)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.postgresql:postgresql"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "42.7.4"
      }, {
        "fixed" : "42.7.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "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" : "WEB",
    "url" : "https://github.com/pgjdbc/pgjdbc/commit/77df98e4e66c12936ded3478a0954f6f580bad99"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ongres/scram/releases/tag/3.3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pgjdbc/pgjdbc"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-636", "CWE-757" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-21T17:47:39Z",
    "nvd_published_at" : "2026-07-06T19:17:08Z"
  }
}