CVE-2026-14672: PostgreSQL observable response discrepancy with non-default scram_iterations provides user existence oracle

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-13 · updated 2026-08-29
Weakness: CWE-204

Description

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 18.6, 17.11, and 16.15 are affected. Versions before PostgreSQL 16 are unaffected.

Affected products

PostgreSQL: from 14.0 before 14.24; from 15.0 before 15.19; from 16.0 before 16.15; from 17.0 before 17.11; from 18.0 before 18.5 — fixed in 14.24, 15.19, 16.15, 17.11, 18.5

How to fix

Upgrade to a fixed version: PostgreSQL 14.24, 15.19, 16.15, 17.11. Check the vendor advisory for mitigations.

References

https://www.postgresql.org/support/security/CVE-2026-14672/

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