CVE-2026-107350

HIGH 8.8

Authentication bypass via second StartupMessage during SCRAM authentication in PgBouncer

CVSS Score

8.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-287
Vendor	n/a
Product	pgbouncer
Published	Oct 14, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Scope

Confidentiality

Integrity

Availability

Affected Versions

n/a / PgBouncer

1.17.0 < 1.26.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

pgbouncer.org: https://www.pgbouncer.org/changelog.html

Credits

Thanks to Dave Aitel (@daveaitel-openai, OpenAI) for finding and reporting this issue.