cbcvebase.
CVE-2016-4553
published 2016-05-10

CVE-2016-4553: client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the Host header when absolute-URI is provided, which allows remote…

PriorityP263high8.6CVSS 3.0
AVNACLPRNUINSCCNIHAN
EPSS
79.97%
99.6th percentile
client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the Host header when absolute-URI is provided, which allows remote attackers to conduct cache-poisoning attacks via an HTTP request.

Affected

16 ranges
VendorProductVersion rangeFixed in
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
debiansquid
oraclelinux
squid-cachesquid<= 3.5.17
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid
squid-cachesquid

Detection & IOCsextracted from sources · hover to see the quote

  • Squid cache poisoning via HTTP request with absolute-URI where Host header is not properly ignored — look for HTTP requests containing an absolute-URI (e.g., 'GET http://example.com/path HTTP/1.1') combined with a differing Host header value sent to a Squid proxy
  • This vulnerability is a bypass of CVE-2009-0801 protections in Squid's intercepted HTTP request handling — detection should focus on intercepted (transparent proxy) HTTP traffic where absolute-URI and Host header disagree
  • Upstream patch available for forensic diffing and rule development: http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
  • Refer to the official Squid advisory SQUID-2016_7 for detailed attack vector and affected configurations
  • ·Only Squid versions before 3.5.18 and 4.x before 4.0.10 are vulnerable; Red Hat Enterprise Linux 5 and 6 packages were assessed as not affected by the vendor
  • ·The vulnerability specifically affects intercepted (transparent proxy) HTTP request handling in Squid, not standard forward-proxy deployments

CVSS provenance

nvdv3.08.6HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:P/A:N
osv8.6HIGH
vendor_debian8.6LOW
vendor_ubuntu8.2HIGH
vendor_redhat5.4MEDIUM
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