CVE-2021-3935

Name: CVE-2021-3935
Creator: NVD / NIST
Published: 2021-11-22T16:15:07.44+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.1/10EPSS 0.96%

Last modified Jun 17, 2026

CVE-2021-3935 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. 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.. EPSS estimates a 0.96% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

8.1/10

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

EPSS Probability

0.96%

57.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Pgbouncer	Pgbouncer	< 1.16.1
Redhat	Enterprise Linux	7.0
Fedoraproject	Fedora	35
Debian	Debian Linux	9.0

References

http://www.pgbouncer.org/changelog.html#pgbouncer-116xRelease Notes, Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2021251Issue Tracking, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/02/msg00016.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNPCV3KRDI5PLLLKADFVIOHACQJLZMLI/
http://www.pgbouncer.org/changelog.html#pgbouncer-116xRelease Notes, Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2021251Issue Tracking, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/02/msg00016.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/05/msg00032.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNPCV3KRDI5PLLLKADFVIOHACQJLZMLI/

Timeline

Published: Nov 22, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3935?

How severe is CVE-2021-3935?

CVE-2021-3935 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.96% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3935?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3935?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST