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SQUID-2020:5 Denial of Service when using SMP cache

High
yadij published GHSA-w7pw-2m4p-58hr Jun 19, 2020

Package

No package listed

Affected versions

5.0.1-5.0.2

Patched versions

5.0.3

Description

Due to an Incorrect Synchronization, Squid is vulnerable to a
Denial of Service attack when processing objects in an SMP cache.


Severity:

This problem may allow a remote client to trigger a Squid worker
assertion.

This attack is limited to SMP Squids using shared memory cache
and/or an SMP rock disk cache.

CVSS Score of 7.3
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C/CR:X/IR:X/AR:H/MAV:N/MAC:H/MPR:L/MUI:N/MS:C/MC:N/MI:X/MA:H&version=3.1


Updated Packages:

This bug is fixed in Squid version 5.0.3.

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

Squid 5:

http://www.squid-cache.org/Versions/v5/SQUID-2020_5.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:

All Squid-3.x up to and including 3.5.28 are not vulnerable.

All Squid-4.x up to and including 4.12 are not vulnerable.

Squid-5.0.1 and 5.0.2 not using SMP caching are not vulnerable.

Squid-5.0.1 and 5.0.2 using SMP caching are vulnerable.


Workarounds:

Disable all SMP caching. For example:

  • If using multiple Squid workers, set 'cache_mem' to '0' and
    remove all cache_dir directives from squid.conf.

  • If using a single Squid worker, remove all 'cache_dir rock'
    directives from squid.conf.


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 your install and build Squid from the original Squid sources
then the squid-users@lists.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 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
squid-bugs@lists.squid-cache.org 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 Jack Zar of Bloomberg.

Fixed by Alex Rousskov of The Measurement Factory.


Revision history:

2020-03-02 16:45:44 UTC Initial Report
2020-05-13 06:37:31 UTC Patch Released


END

Severity

High

CVE ID

CVE-2020-14059

Weaknesses

No CWEs