CVE-2021-3935 SQL injection in pgbouncer

What is CVE-2021-3935?

CVE-2021-3935 is a high-severity SQL injection vulnerability in Debian Debian Linux, published on 22 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-295, CWE-89

Which versions are affected by CVE-2021-3935?

1 open source package ship an affected version, including pgbouncer. It affects 4 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Pgbouncer Pgbouncer, Redhat Enterprise Linux.

How do I fix CVE-2021-3935?

Upgrade pgbouncer to 1.16.1 or later.

Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.

Is CVE-2021-3935 being exploited?

There is no known exploitation of CVE-2021-3935 in the wild and no public exploit code.

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• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-pgbouncer-2021-3935, CLEANSTART-2026-MZ91907, DEBIAN-CVE-2021-3935, DLA-2922-1, GHSA-jh4v-gqwq-hfrr, UBUNTU-CVE-2021-3935.