CVE-2026-107350

Authentication bypass via second StartupMessage during SCRAM authentication in PgBouncer

CVE-2026-107350 is fixed in pgbouncer on 1 platform by DEBIAN-CVE-2026-107350 (version 1.26.1-1), released October 16, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

8.8

Important

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0037

30th percentile

Improper authentication in PgBouncer 1.17.0 through 1.26.0 allows a remote attacker who knows the password of a user listed in auth_file to log in as any other user that authenticates using SCRAM, including PgBouncer admin users and backend superusers. A second StartupMessage sent during SCRAM authentication against a non-existent database is not rejected and switches the user being logged in as, while the SCRAM exchange is still verified against the keys of the first user.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
pgbouncer · Debian 14	1.26.1-1	DEBIAN-CVE-2026-107350	Oct 16, 2026

Details

Published
October 14, 2026
Weakness
Improper Authentication
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-107350

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