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Servers and applications

CVE-2021-41611

SQUID-2021:6 Improper Certificate Validation of TLS server certificates

Severity
High 7.5
Published
4 Oct 2021
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Fixed in
5.2
Also known as
GHSA-47m4-g3mv-9q5r
Sources
NVD, Project advisories (GitHub)

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.

Affected software

SoftwareAffected versions
SquidServers and applications · cpe:a:squid-cache:squid
  • From 5.0.6 before 5.2
SquidServers and applications · github:squid-cache/squid
  • From 5.0.6 before 5.2

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2021-41611
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2021-41611
  • GitHub Advisory Database https://github.com/advisories/GHSA-47m4-g3mv-9q5r
  • github.com https://github.com/squid-cache/squid/security/advisories/GHSA-47m4-g3mv-9q5r