CVE-2019-12520

Published: 15 April 2020

An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.

Priority

Medium

CVSS 3 base score: 7.5

Status

Package Release Status
squid
Launchpad, Ubuntu, Debian
Upstream
Released (4.8)
Ubuntu 21.04 (Hirsute Hippo) Not vulnerable
(4.10-1ubuntu1)
Ubuntu 20.04 LTS (Focal Fossa) Not vulnerable
(4.10-1ubuntu1)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

Patches:
Upstream: http://www.squid-cache.org/Versions/v4/changesets/SQUID-2019_4.patch
squid3
Launchpad, Ubuntu, Debian
Upstream Needs triage

Ubuntu 21.04 (Hirsute Hippo) Does not exist

Ubuntu 20.04 LTS (Focal Fossa) Does not exist

Ubuntu 18.04 LTS (Bionic Beaver)
Released (3.5.27-1ubuntu1.7)
Ubuntu 16.04 ESM (Xenial Xerus) Not vulnerable
(code not present)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist