No exploitation reportedFix available

CVE-2021-3935

Q: Is CVE-2021-3935 actively exploited?

Active exploitation of CVE-2021-3935 has not been confirmed. Its EPSS score was 1.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-3935?

CVE-2021-3935 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-11-22
WeaknessCWE-295 · CWE-89

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2021-11-2216:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-3935?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-3935?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Debian debian linux

Branch	Affected	Fixed in	Source
9.0	= 9.0	no fix published	NVD

Fedoraproject fedora

Branch	Affected	Fixed in	Source
35.x	= 35	no fix published	NVD

Pgbouncer

Branch	Affected	Fixed in	Source
1.16	< 1.16.1	1.16.1	NVD · OSV

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

www.pgbouncer.orgRelease Notes · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.1read 2026-10-23
NVDCVSS 2.05.1read 2026-10-23
CNAweakness (CWE)CWE-89read 2026-10-23
NVDweakness (CWE)CWE-295read 2026-10-23
FIRST EPSSEPSS score1.1 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-11-22
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-3935?

Is CVE-2021-3935 actively exploited?

Active exploitation of CVE-2021-3935 has not been confirmed. Its EPSS score was 1.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3935?

CVE-2021-3935 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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