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Squid Proxy Cache Security Update Advisory SQUID-2020:13
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Advisory ID: | SQUID-2020:13
Date: | September 06, 2023
Summary: | Denial of Service in gopher gateway
Affected versions: | Squid 2.x -> 2.7.STABLE9
| Squid 3.x -> 3.5.28
| Squid 4.x -> 4.14
| Squid 5.x -> 5.6
Fixed in version: | Squid 6.0.1
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Problem Description:
Due to a buffer overflow bug Squid is vulnerable to a Denial of Service
attack against Squid's gopher gateway.
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Severity:
This problem allows a remote gopher: server to trigger a buffer
overflow by delivering large gopher protocol responses.
On most operating systems with memory protection this will
halt Squid service immediately, causing a denial of service to
all Squid clients.
The gopher protocol is always available and enabled in Squid
prior to Squid 6.0.1
Responses triggering this bug are possible to be received from
any gopher server, even those without malicious intent.
CVSS Score of 7.5
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1>
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Updated Packages:
The gopher support has been removed in Squid version 6.0.1
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-2.x up to and including 2.7.STABLE9 are vulnerable.
All Squid-3.x up to and including 3.5.28 are vulnerable.
All Squid-4.x up to and including 4.14 are vulnerable.
All Squid-5.x up to and including 5.6 are vulnerable.
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Workaround:
* Reject all gopher URL requests
acl gopher proto gopher
http_access deny gopher
Note: removing the gopher port 70 from the Safe_ports ACL
is not sufficient to avoid this vulnerability.
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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-us...@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
<https://bugs.squid-cache.org/>.
For reporting of security sensitive bugs send an email to the
<squid-b...@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.
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Credits:
This vulnerability was discovered by Marco Grassi.
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Revision history:
2019-06-15 13:32:50 UTC Initial Report
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END
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