cPanel Perl Encode.pm CVE-2021-36770

Background Information

On August 9th, 2021, Perl announced a vulnerability in the Encode.pm Perl module version 3.05. 

Impact

According to Perl development: Porters,I have attached a fix for a bug in Encode, registered as CVE-2021-36770.  This bug replaces the contents of @INC with a predictable integer, which is treated as a directory relative to the current working directory, long enough to execute one “require”.The vulnerability was introduced in Encode v3.05, here: dankogai/[email protected]  It was shipped with Perl v5.32 and v5.34.A simple proof of concept:

dinah:~/tmp$ perl -MEncode -e0 
dinah:~/tmp$ perl -E 'say scalar @INC'
4
dinah:~/tmp$ mkdir -p 4/Encode
dinah:~/tmp$ echo 'print "Something evil here!!\n"' > 4/Encode/ConfigLocal.pm
dinah:~/tmp$ perl -MEncode -e0
Something evil here!!

A new release of Encode should be available from the CPAN today and will be swiftly integrated into perl5.git.  I expect this fix will shortly be available from major distributors of Perl.  In the meantime, I have applied a patch to the repository.This bug was reported to perlsec on June 26 by Dom Hargreaves on behalf of Debian, passing on a report from Paul Wise. — rjbs

Releases

Versions greater than or equal to the versions listed below include the updated Encode.pm perl module.

11.94 – 11.94.0.15
11.96 – 11.96.0.15
11.98 – 11.98.0.4

How to determine if your server is up-to-date

For versions 94 and greater, the previously updated RPMs provided by cPanel will contain a changelog entry noting the applied fixes.
You can check for the changelog entry in versions 94 and greater with the following command:

rpm -q --changelog cpanel-perl-532-encode | grep "Encode 3.12"

The output should resemble below:

- Update patches: Encode 3.12 - Update from upstream: Encode 3.12

What to do if you are not up-to-date

If your server is not running one of the above versions, update immediately.To upgrade your server, navigate to WHM’s  Upgrade to Latest Version interface ( Home >> cPanel >> Upgrade to Latest Version ) and click Click to Upgrade.To upgrade cPanel from the command line, run the following commands:

/scripts/upcp /scripts/check_cpanel_rpms --fix --long-list

For versions 94 and greater, verify the updated Perl RPM was installed:

rpm -q --changelog cpanel-perl-532-encode | grep "Encode 3.12"

The output should resemble below:

- Update patches: Encode 3.12 - Update from upstream: Encode 3.12

Additional Information

Credit: This bug was reported to perlsec on June 26 by Dom Hargreaves on behalf of Debian, passing on a report from Paul Wise. CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-36770For the signed PGP Version of this message: Unscheduled-TSR-8_10_21-CVE-2021-36770.signed

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