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Squid Proxy Cache Security Update Advisory SQUID-2021:7
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Advisory ID: | SQUID-2021:7
Date: | Jun 06, 2022
Summary: | Denial of Service in Gopher Processing
Affected versions: | Squid 3.x -> 3.5.28
| Squid 4.x -> 4.17
| Squid 5.x -> 5.5
Fixed in version: | Squid 5.6
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<http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-46784>
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### Problem Description:
Due to improper buffer management Squid is vulnerable to a Denial
of Service attack when processing Gopher server responses.
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### Severity:
This problem allows a remote server to perform Denial of Service
when processing Gopher responses.
CVSS Score of 9.8
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H/E:X/RL:X/RC:C/CR:X/IR:X/AR:H/MAV:N/MAC:L/MPR:N/MUI:X/MS:U/MC:X/MI:X/MA:H&version=3.1>
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### Updated Packages:
#### This bug is fixed by Squid version 5.6.
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/changesets/SQUID-2021_7.patch>
#### Squid 5:
<http://www.squid-cache.org/Versions/v5/changesets/SQUID-2021_7.patch>
If you are using a prepackaged version of Squid then please refer
to the package vendor for availability information on updated
packages.
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### Determining if your version is vulnerable:
All Squid-3.x up to and including 3.5.28 are vulnerable.
All Squid-4.x up to and including 4.17 are vulnerable.
All Squid-5.x up to and including 5.5 are vulnerable.
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### Workaround:
Deny access to gopher:// resources by adding the following lines
to the top of squid.conf:
acl gopher proto gopher
http_access deny gopher
Please be mindful that removing port 70 from the Safe_ports ACL
definition is not sufficient. A malicious actor may easily
operate gopher servers on other ports.
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### 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@xxxxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxx> 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.
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### Credits:
This vulnerability was discovered and fixed by Joshua Rogers of
Opera Software.
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### Revision history:
2021-02-20 23:38:06 UTC Initial Report
2022-04-18 13:42:36 UTC Patch Released
2022-04-21 08:29:13 UTC CVE Allocation
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END
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