cbcvebase.
CVE-2021-33620
published 2021-05-28

CVE-2021-33620: 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…

PriorityP350medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
EPSS
79.58%
99.6th percentile
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

11 ranges
VendorProductVersion rangeFixed in
debiandebian_linux
debiansquid< squid 4.13-10 (bookworm)squid 4.13-10 (bookworm)
fedoraprojectfedora
fedoraprojectfedora
squid-cachesquid< 4.154.15
squid-cachesquid>= 5.0 < 5.0.65.0.6
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.10-1ubuntu1.44.10-1ubuntu1.4

Detection & IOCsextracted from sources · hover to see the quote

  • Vulnerable versions of Squid are before 4.15 and 5.x before 5.0.6; detect these versions in use as a proxy to identify exposure to this DoS via HTTP response header processing
  • The DoS trigger is a specific HTTP response header that can appear in normal traffic; monitor Squid proxy processes for unexpected crashes or availability loss correlated with upstream HTTP responses containing unusual headers
  • The vulnerability is an input validation flaw in HTTP response message processing; monitor Squid logs for repeated failed responses from upstream servers coinciding with proxy-wide client unavailability
  • ·No mitigation is available from Red Hat; patching to Squid 4.15+ or 5.0.6+ is the only remediation
  • ·Red Hat Enterprise Linux 9 is not affected; RHEL 6 and 7 are out of support scope for this moderate-rated flaw
  • ·Debian fixed this in squid package version 4.13-10 across bookworm, bullseye, forky, sid, and trixie

CVSS provenance

nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvdv2.04.0MEDIUMAV:N/AC:L/Au:S/C:N/I:N/A:P
osv7.5HIGH
vendor_ubuntu7.5HIGH
vendor_debian6.5MEDIUM
vendor_redhat6.5MEDIUM
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