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Vulnerability Assessment Details
Squid ACL [url_regex] bypass vulnerability
Detailed Explanation for this Vulnerability Assessment
The remote host is affected by the vulnerability described in GLSA-200403-11
(Squid ACL [url_regex] bypass vulnerability)
A bug in Squid permits 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 permit 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.
Squid can be updated as follows:
# emerge sync
# emerge -pv ">=www-proxy/squid-2.5.5"
# emerge ">=www-proxy/squid-2.5.5"
Network Security Threat Level: Medium
Networks Security ID:
Vulnerability Assessment Copyright: (C) 2005 Michel Arboi
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