Bug 1731412 (CVE-2019-13917)

Summary: CVE-2019-13917 exim: ${sort} in configuration leads to privilege escalation
Product: [Other] Security Response Reporter: Dhananjay Arunesh <darunesh>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: bennie.joubert, dwmw2, jskarvad, security-response-team, tremble
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: exim 4.92.1 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-07-22 05:16:24 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1733410, 1733411    
Bug Blocks: 1731414    

Description Dhananjay Arunesh 2019-07-19 11:06:16 UTC
A flaw was found in exim, in which if the server configuration uses the ${sort } expansion, then this could be controlled by the remote attacker (e.g. $local_part, $domain), resulting in the attacker able to execute programs with root privileges.

Note: The default config, as shipped by exim upstream, does not contain ${sort }.

exim versions from 4.85 up to and including 4.92 are affected.

Comment 1 Huzaifa S. Sidhpurwala 2019-07-22 05:08:12 UTC
Acknowledgments:

Name: Jeremy Harris

Comment 2 Huzaifa S. Sidhpurwala 2019-07-22 05:08:18 UTC
Statement:

As per upstream, this exim security flaw only affects exim versions from 4.85 up to and including 4.92. Since Red Hat Enterprise Linux 5 ships exim-4.63, it is not affected by this flaw.

Comment 3 Huzaifa S. Sidhpurwala 2019-07-22 05:08:22 UTC
Mitigation:

Do not use ${sort } in your exim configuration.

Comment 4 Huzaifa S. Sidhpurwala 2019-07-26 03:31:12 UTC
External References:

https://www.exim.org/static/doc/security/CVE-2019-13917.txt

Comment 5 Huzaifa S. Sidhpurwala 2019-07-26 03:31:45 UTC
Created exim tracking bugs for this issue:

Affects: epel-all [bug 1733411]
Affects: fedora-all [bug 1733410]