__________________________________________________________________
Squid Proxy Cache Security Update Advisory SQUID-2024:2
__________________________________________________________________
Advisory ID: | SQUID-2024:2
Date: | Feb 15, 2024
Summary: | Denial of Service in HTTP Header parser
Affected versions: | Squid 3.x -> 3.5.28
| Squid 4.x -> 4.17
| Squid 5.x -> 5.9
| Squid 6.x -> 6.4
Fixed in version: | Squid 6.5
__________________________________________________________________
Problem Description:
Due to a Collapse of Data into Unsafe Value bug,
Squid may be vulnerable to a Denial of Service
attack against HTTP header parsing.
__________________________________________________________________
Severity:
This problem allows a remote client or a remote server to
perform Denial of Service when sending oversized headers in
HTTP messages.
In versions of Squid prior to 6.5 this can be achieved if the
request_header_max_size or reply_header_max_size settings are
unchanged from the default.
In Squid version 6.5 and later, the default setting of these
parameters is safe. Squid will emit a critical warning in
cache.log if the administrator is setting these parameters to
unsafe values. Squid will not at this time prevent these settings
from being changed to unsafe values.
__________________________________________________________________
Updated Packages:
Hardening against this issue is added to Squid version 6.5.
In addition, patches addressing this problem for the stable
releases can be found in our patch archives:
Squid 6:
<http://www.squid-cache.org/Versions/v6/SQUID-2024_2.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:
Run the following command to identify how (and whether)
your Squid has been configured with relevant settings:
squid -k parse 2>&1 | grep header_max_size
All Squid-3.0 up to and including 6.4 without header_max_size
settings are vulnerable.
All Squid-3.0 up to and including 6.4 with either header_max_size
setting over 21 KB are vulnerable.
All Squid-3.0 up to and including 6.4 with both header_max_size
settings below 21 KB are not vulnerable.
All Squid-6.5 and later without header_max_size configured
are not vulnerable.
All Squid-6.5 and later configured with both header_max_size
settings below 64 KB are not vulnerable.
All Squid-6.5 and later configured with either header_max_size
setting over 64 KB are vulnerable.
__________________________________________________________________
Workaround:
For Squid older than 6.5, add to squid.conf:
request_header_max_size 21 KB
reply_header_max_size 21 KB
For Squid 6.5 and later, remove request_header_max_size
and reply_header_max_size 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 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
<https://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.
__________________________________________________________________
Credits:
This vulnerability was discovered by Joshua Rogers of Opera
Software.
Fixed by The Measurement Factory.
__________________________________________________________________
Revision history:
2023-10-12 11:53:02 UTC Initial Report
2023-10-25 11:47:19 UTC Patches Released
__________________________________________________________________
END
_______________________________________________
squid-announce mailing list
squid-announce@xxxxxxxxxxxxxxxxxxxxx
https://lists.squid-cache.org/listinfo/squid-announce
