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SQUID-2021:5 Denial of Service in HTTP Response processing

Moderate
yadij published GHSA-572g-rvwr-6c7f May 10, 2021

Package

squid (Squid)

Affected versions

< 4.15, 5.0-5.0.5

Patched versions

4.15, 5.0.6

Description

Due to an input validation bug Squid is vulnerable to a Denial
of Service against all clients using the proxy.


Severity:

This problem allows a remote server to perform Denial of Service
when delivering HTTP Response messages. The issue trigger is a
header which can be expected to exist in HTTP traffic without
any malicious intent by the server

CVSS Score of 8.8
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C/CR:X/IR:X/AR:H/MAV:N/MAC:L/MPR:L/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_5.patch

Squid 5:

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

Squid older than 4.15 have not been tested and should be
assumed to be vulnerable.

All Squid-5.x up to and including 5.0.5 are vulnerable.


Workaround:

There are no known workarounds to this 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@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 Joshua Rogers of Opera
Software.

Fixed by Alex Rousskov of The Measurement Factory.


Revision history:

2021-03-05 22:11:43 UTC Initial Report
2021-05-28 11:29:59 UTC CVE Assignment


END

Severity

Moderate
6.5
/ 10

CVSS base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2021-33620

Weaknesses

No CWEs