UpHeron
All vulnerabilities

Servers and applications

CVE-2021-33620

SQUID-2021:5 Denial of Service in HTTP Response processing

Severity
Medium 6.5
Published
10 May 2021
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Fixed in
4.15, 5.0.6
Also known as
GHSA-572g-rvwr-6c7f
Sources
NVD, Project advisories (GitHub)

Description

Squid before 4.15 and 5.x before 5.0.6 allows remote servers to cause a denial of service (affecting availability to all clients) via an HTTP response. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent by the server.

Affected software

SoftwareAffected versions
SquidServers and applications · cpe:a:squid-cache:squid
  • Every version before 4.15
  • From 5.0 before 5.0.6
SquidServers and applications · github:squid-cache/squid
  • From 5.0 before 4.15

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2021-33620
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2021-33620
  • GitHub Advisory Database https://github.com/advisories/GHSA-572g-rvwr-6c7f
  • github.com https://github.com/squid-cache/squid/security/advisories/GHSA-572g-rvwr-6c7f