Medium [CVE-2026-14672] User existence oracle in SCRAM authentication
This medium-severity Red Hat Linux advisory covers CVE-2026-14672 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
Observable response discrepancy in PostgreSQL SCRAM authentication allows an unauthenticated user to test the existence of a user via observing the SCRAM iteration count. This requires the probed user to have a non-default scram_iterations count, because the authentication challenge for a nonexistent user reports the default scram_iterations.
Within major versions 16-18, minor versions before PostgreSQL 18.5, 17.11, and 16.15 are affected. Unauthenticated attackers can verify if a specific user exists by observing the authentication iteration count, provided the targeted user is configured with a non-default scram_iterations value.
A moderate-severity vulnerability in PostgreSQL allows unauthenticated attackers to enumerate valid users. By observing discrepancies in SCRAM authentication responses, attackers can identify users configured with a non-default scram_iterations count, which may facilitate targeted brute-force attacks.
Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N). Weakness: CWE-204.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: postgresql16; Red Hat package: postgresql18.
- < 18.5
- < 17.11
- < 16.15
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- To mitigate this information disclosure, ensure all PostgreSQL users are configured with the default `scram_iterations` count. This prevents the observable response discrepancy that allows an unauthenticated user to determine user existence. Additionally, restrict network access to the PostgreSQL service to only trusted clients and networks by configuring firewall rules to limit inbound connections to the PostgreSQL port (default 5432). If firewall rules are modified, a service reload or restart may be required for changes to take effect.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
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