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 attackers to conduct cache-poisoning attacks via an HTTP request.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 80.0%, higher than 100% of all known CVEs. Patch or mitigate before the next change window.
Description
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.
- CVSS 3.0
- 8.6 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
- EPSS
- 79.97% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-345
- Affected
- canonical/ubuntu linux · squid-cache/squid · oracle/linux
- Source
- cve@mitre.org
EPSS moved from 78.8% on 21 September 2026 to 80.0% on 4 November 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- http://bugs.squid-cache.org/show_bug.cgi?id=4501Vendor Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
- http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
- http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
- http://www.debian.org/security/2016/dsa-3625
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.htmlThird Party Advisory
- http://www.securitytracker.com/id/1035768Third Party Advisory
- http://www.squid-cache.org/Advisories/SQUID-2016_7.txtVendor Advisory
- http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
- http://www.ubuntu.com/usn/USN-2995-1Third Party Advisory
- https://access.redhat.com/errata/RHSA-2016:1139
- https://access.redhat.com/errata/RHSA-2016:1140
- https://security.gentoo.org/glsa/201607-01
- http://bugs.squid-cache.org/show_bug.cgi?id=4501Vendor Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
- http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
- http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
- http://www.debian.org/security/2016/dsa-3625
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.htmlThird Party Advisory
- http://www.securitytracker.com/id/1035768Third Party Advisory
- http://www.squid-cache.org/Advisories/SQUID-2016_7.txtVendor Advisory
- http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-14039.patch
- http://www.ubuntu.com/usn/USN-2995-1Third Party Advisory
- https://access.redhat.com/errata/RHSA-2016:1139
- https://access.redhat.com/errata/RHSA-2016:1140
- https://security.gentoo.org/glsa/201607-01
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.