GLSA-200403-11 : Squid ACL [url_regex] bypass vulnerability
High Nessus Plugin ID 14462
SynopsisThe remote Gentoo host is missing one or more security-related patches.
DescriptionThe remote host is affected by the vulnerability described in GLSA-200403-11 (Squid ACL [url_regex] bypass vulnerability)
A bug in Squid allows users to bypass certain access controls by passing a URL containing '%00' which exploits the Squid decoding function.
This may insert a NUL character into decoded URLs, which may allow users to bypass url_regex access control lists that are enforced upon them.
In such a scenario, Squid will insert a NUL character after the'%00' and it will make a comparison between the URL to the end of the NUL character rather than the contents after it: the comparison does not result in a match, and the user's request is not denied.
Restricted users may be able to bypass url_regex access control lists that are enforced upon them which may cause unwanted network traffic as well as a route for other possible exploits. Users of Squid 2.5STABLE4 and below who require the url_regex features are recommended to upgrade to 2.5STABLE5 to maintain the security of their infrastructure.
A workaround is not currently known for this issue. All users are advised to upgrade to the latest version of Squid.
SolutionSquid can be updated as follows:
# emerge sync # emerge -pv '>=net-proxy/squid-2.5.5' # emerge '>=net-proxy/squid-2.5.5'