__________________________________________________________________ Squid Proxy Cache Security Update Advisory SQUID-2019:8 __________________________________________________________________ Advisory ID: SQUID-2019:8 Date: November 05, 2019 Summary: Multiple issues in URI processing. Affected versions: Squid 3.x -> 3.5.28 Squid 4.x -> 4.8 Fixed in version: Squid 4.9 __________________________________________________________________ http://www.squid-cache.org/Advisories/SQUID-2019_8.txt http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-12523 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18676 __________________________________________________________________ Problem Description: Due to improper input validation Squid is vulnerable to security bypass attacks. Attacker can gain access to restricted HTTP servers. Due to incorrect input validation Squid is vulnerable to a buffer overflow which can result in Denial of Service to all clients using the proxy. __________________________________________________________________ Severity: Any remote client may access resources which should be restricted and not available to them. Such as those protected behind client IP ACLs. Attacker could also gain access to manager services when Via header is turned off. Any remote client can perform a Denial of Service on all other clients using the proxy. __________________________________________________________________ Updated Packages: These bugs are fixed by Squid version 4.9. In addition, a patch addressing this problem for stable releases can be found in our patch archives: Squid 4: If you are using a prepackaged version of Squid then please refer to the package vendor for availability information on updated packages. __________________________________________________________________ Determining if your version is vulnerable: Use the command 'squid -v' to view version and build details of your proxy; All Squid 2.x have not been checked. All Squid-3.x up to and including 3.5.28 are vulnerable. All Squid-4.x up to and including 4.8 are vulnerable. __________________________________________________________________ Workaround: Access to manager services can be prevented by enabling the Via header: via on There are no reliable workarounds to prevent access to restricted upstream servers. There are no workarounds for the Denial of Service issue. __________________________________________________________________ Contact details for the Squid project: For installation / upgrade support on binary packaged versions of Squid: Your first point of contact should be your binary package vendor. If you install and build Squid from the original Squid sources then the squid-users@squid-cache.org mailing list is your primary support point. For subscription details see http://www.squid-cache.org/Support/mailing-lists.html. For reporting of non-security bugs in the latest release the squid bugzilla database should be used http://bugs.squid-cache.org/. For reporting of security sensitive bugs send an email to the squid-bugs@squid-cache.org mailing list. It is a closed list (though anyone can post) and security related bug reports are treated in confidence until the impact has been established. __________________________________________________________________ Credits: The security bypass vulnerability was discovered by Jeriko One . The Denial of Service vulnerability was discovered by Kristoffer Danielsson. Fixed by Amos Jeffries, Treehouse Networks Ltd. __________________________________________________________________ Revision history: 2019-05-14 14:56:49 UTC Initial Report 2019-06-05 15:52:17 UTC CVE-2019-12523 Assignment 2019-07-03 01:07:41 UTC Additional Report 2019-11-04 13:43:22 UTC CVE-2019-18676 Assignment __________________________________________________________________ END