Due to an incorrect parser validation bug Squid is vulnerable to
a Denial of Service attack against the Cache Manager API.

Severity:

This problem allows a trusted client to trigger memory leaks
which over time lead to a Denial of Service against Squid and
the machine it is operating on.

This attack is limited to clients with Cache Manager API access
privilege.

CVSS Score of 7.8
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H/E:F/RL:O/RC:C/CR:X/IR:X/AR:H/MAV:N/MAC:H/MPR:H/MUI:N/MS:C/MC:X/MI:X/MA:H&version=3.1

Updated Packages:

This bug is fixed by Squid versions 4.15 and 5.0.6.

In addition, patches addressing this problem for the stable
releases can be found in our patch archives:

Squid 4:

http://www.squid-cache.org/Versions/v4/SQUID-2021_3.patch

Squid 5:

http://www.squid-cache.org/Versions/v5/SQUID-2021_3.patch

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:

Squid older than 3.5.28 have not been tested and should be
assumed to be vulnerable.

All Squid-4.x up to and including 4.14 are vulnerable.

All Squid-5.x up to and including 5.0.4 are vulnerable.

Workaround:

Either,

Disable Cache Manager access entirely if not needed.

Place the following line in squid.conf before lines containing
"allow" :

http_access deny manager

Or,

Harden Cache Manager access privileges.

For example; require authentication or other access controls in
http_access beyond the default IP address restriction.

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 [email protected] 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 STABLE release
the squid bugzilla database should be used
http://bugs.squid-cache.org/.

For reporting of security sensitive bugs send an email to the
[email protected] mailing list. It's a closed
list (though anyone can post) and security related bug reports
are treated in confidence until the impact has been established.

Credits:

This vulnerability was discovered by Joshua Rogers of Opera
Software.

Fixed by Amos Jeffries of Treehouse Networks Ltd.

Revision history:

2021-03-03 17:02:25 UTC Initial Report
2021-03-16 01:59:45 UTC Patch Released
2021-03-17 06:19:09 UTC CVE Assignment

END