CVE-2021-3935

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-22 · updated 2026-06-17
Weakness: CWE-89

Description

When PgBouncer is configured to use "cert" authentication, a man-in-the-middle attacker can inject arbitrary SQL queries when a connection is first established, despite the use of TLS certificate verification and encryption. This flaw affects PgBouncer versions prior to 1.16.1.

Affected products

Debian Linux: 9.0
Fedoraproject Fedora: 35
PgBouncer: before 1.16.1 — fixed in 1.16.1
Red Hat Enterprise Linux: 7.0

How to fix

Upgrade to a fixed version: PgBouncer 1.16.1. Check the vendor advisory for mitigations.

References

http://www.pgbouncer.org/changelog.html#pgbouncer-116x
https://bugzilla.redhat.com/show_bug.cgi?id=2021251
https://lists.debian.org/debian-lts-announce/2022/02/msg00016.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNPCV3KRDI5PLLLKADFVIOHACQJLZMLI/
http://www.pgbouncer.org/changelog.html#pgbouncer-116x
https://bugzilla.redhat.com/show_bug.cgi?id=2021251
https://lists.debian.org/debian-lts-announce/2022/02/msg00016.html
https://lists.debian.org/debian-lts-announce/2025/05/msg00032.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNPCV3KRDI5PLLLKADFVIOHACQJLZMLI/

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