Vulnerability · Published Oct 14, 2026 · Assigned by PostgreSQL
CVE-2026-107350Authentication bypass via second StartupMessage during SCRAM authentication in PgBouncer
High 8.8
In plain English
A high-severity improper authentication in PgBouncer. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pgbouncer | no fix listed | DEBIAN-CVE-2026-107350 |
| Debian:13 | pgbouncer | no fix listed | DEBIAN-CVE-2026-107350 |
| Debian:14 | pgbouncer | 1.26.1-1 | DEBIAN-CVE-2026-107350 |
| Ubuntu:22.04:LTS | pgbouncer | no fix listed | UBUNTU-CVE-2026-107350 |
| Ubuntu:24.04:LTS | pgbouncer | no fix listed | UBUNTU-CVE-2026-107350 |
| Ubuntu:26.04:LTS | pgbouncer | no fix listed | UBUNTU-CVE-2026-107350 |
| Ubuntu:26.10 | pgbouncer | no fix listed | UBUNTU-CVE-2026-107350 |
Affected products (as reported)
Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H