Squid » Squid : Security Vulnerabilities, CVEs, CVSS score >= 7

Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.

Gibraltar Firewall 2.2 and earlier, when using the ClamAV update to 0.81 for Squid, uses a defunct ClamAV method to scan memory for viruses, which does not return an error code and prevents viruses from being detected.

Squid 2.5.STABLE9 and earlier does not trigger a fatal error when it identifies missing or invalid ACLs in the http_access configuration, which could lead to less restrictive ACLs than intended by the administrator.

Squid 2.5, when processing the configuration file, parses empty Access Control Lists (ACLs), including proxy_auth ACLs without defined auth schemes, in a way that effectively removes arguments, which could allow remote attackers to bypass intended ACLs if the administrator ignores the parser warnings.

squid_ldap_auth in Squid 2.5 and earlier allows remote authenticated users to bypass username-based Access Control Lists (ACLs) via a username with a space at the beginning or end, which is ignored by the LDAP server.

The "%xx" URL decoding function in Squid 2.5STABLE4 and earlier allows remote attackers to bypass url_regex ACLs via a URL with a NULL ("%00") character, which causes Squid to use only a portion of the requested URL when comparing it against the access control lists.

FTP proxy in Squid before 2.4.STABLE6 does not compare the IP addresses of control and data connections with the FTP server, which allows remote attackers to bypass firewall rules or spoof FTP server responses.

Buffer overflows in Squid before 2.4.STABLE6 allow remote attackers to cause a denial of service (crash) and possibly execute arbitrary code (1) via the MSNT auth helper (msnt_auth) when using denyusers or allowusers files, (2) via the gopher client, or (3) via the FTP server directory listing parser when HTML output is generated.

Heap-based buffer overflow in Squid before 2.4 STABLE4, and Squid 2.5 and 2.6 until March 12, 2002 distributions, allows remote attackers to cause a denial of service, and possibly execute arbitrary code, via compressed DNS responses.

Squid 2.4 STABLE3 and earlier allows remote attackers to cause a denial of service (core dump) and possibly execute arbitrary code with an ftp:// URL with a larger number of special characters, which exceed the buffer when Squid URL-escapes the characters.

Squid 2.4 STABLE3 and earlier does not properly disable HTCP, even when "htcp_port 0" is specified in squid.conf, which could allow remote attackers to bypass intended access restrictions.