# 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-107350
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0037
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 14, 2026
- Weakness: Improper Authentication
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-107350

## Description

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

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | pgbouncer Debian 14 | 1.26.1-1 | [DEBIAN-CVE-2026-107350](https://patchblox.com/security/data/fix/linux/debian-cve-2026-107350.md) | Oct 16, 2026 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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