CVE-2021-41611

Name: CVE-2021-41611
Creator: NVD / NIST
Published: 2021-10-18T09:15:08.823+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.85%

Last modified Jun 17, 2026

CVE-2021-41611 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An issue was discovered in Squid 5.0.6 through 5.1.x before 5.2. When validating an origin server or peer certificate, Squid may incorrectly classify certain certificates as trusted. EPSS estimates a 2.85% chance of exploitation in the next 30 days.

Description

An issue was discovered in Squid 5.0.6 through 5.1.x before 5.2. When validating an origin server or peer certificate, Squid may incorrectly classify certain certificates as trusted. This problem allows a remote server to obtain security trust well improperly. This indication of trust may be passed along to clients, allowing access to unsafe or hijacked services.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.85%

84.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-295

Affected Software

Vendor	Product	Versions
Squid-Cache	Squid	>= 5.0.6, < 5.2
Fedoraproject	Fedora	35

References

http://www.openwall.com/lists/oss-security/2021/12/23/2Mailing List, Third Party Advisory
http://www.squid-cache.org/Versions/v6/changesets/squid-6-43d6b5c81b88ec2256b430c69a872a1e4f324e4a.patchVendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-47m4-g3mv-9q5rPatch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CWQ2WKDWTSO47S3F6XJJ6HGG2ULWEAE4/
http://www.openwall.com/lists/oss-security/2021/12/23/2Mailing List, Third Party Advisory
http://www.squid-cache.org/Versions/v6/changesets/squid-6-43d6b5c81b88ec2256b430c69a872a1e4f324e4a.patchVendor Advisory
https://github.com/squid-cache/squid/security/advisories/GHSA-47m4-g3mv-9q5rPatch, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CWQ2WKDWTSO47S3F6XJJ6HGG2ULWEAE4/

Timeline

Published: Oct 18, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-41611?

How severe is CVE-2021-41611?

CVE-2021-41611 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.85% probability of exploitation in the next 30 days.

How do I fix CVE-2021-41611?

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-2021-41611?

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

Scan your code now

Source: NVD / NIST