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Squid: Remote DoS vulnerability


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200410-15 / squid
Release Date October 18, 2004
Latest Revision December 30, 2007: 03
Impact normal
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
net-proxy/squid < 2.5.7 >= 2.5.7 All supported architectures

Related bugreports: #67167


Squid contains a vulnerability in the SNMP module which may lead to a denial of service.

2.  Impact Information


Squid is a full-featured Web proxy cache designed to run on Unix systems. It supports proxying and caching of HTTP, FTP, and other URLs, as well as SSL support, cache hierarchies, transparent caching, access control lists and many other features.


A parsing error exists in the SNMP module of Squid where a specially-crafted UDP packet can potentially cause the server to restart, closing all current connections. This vulnerability only exists in versions of Squid compiled with the 'snmp' USE flag.


An attacker can repeatedly send these malicious UDP packets to the Squid server, leading to a denial of service.

3.  Resolution Information


Disable SNMP support or filter the port that has SNMP processing (default is 3401) to allow only SNMP data from trusted hosts.

To disable SNMP support put the entry snmp_port 0 in the squid.conf configuration file.

To allow only the local interface to process SNMP, add the entry "snmp_incoming_address" in the squid.conf configuration file.


All Squid users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge sync

# emerge -pv ">=net-proxy/squid-2.5.7"
# emerge ">=net-proxy/squid-2.5.7"

4.  References


Page updated October 18, 2004

Summary: This is a Gentoo Linux Security Advisory

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