Bug 1517680 (CVE-2017-16943) - CVE-2017-16943 exim: use-after-free in receive_msg function via vectors involving BDAT commands
Summary: CVE-2017-16943 exim: use-after-free in receive_msg function via vectors invol...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2017-16943
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
urgent
urgent
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1517686 1517687
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-11-27 08:47 UTC by Adam Mariš
Modified: 2021-02-17 01:11 UTC (History)
4 users (show)

Fixed In Version:
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Last Closed: 2017-11-27 09:02:33 UTC
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Description Adam Mariš 2017-11-27 08:47:06 UTC 
The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) via vectors involving BDAT commands.

Upstream bug:

https://bugs.exim.org/show_bug.cgi?id=2199

Upstream patch:

https://git.exim.org/exim.git/commitdiff/4e6ae6235c68de243b1c2419027472d7659aa2b4
Comment 1 Adam Mariš 2017-11-27 08:54:14 UTC 
Created exim tracking bugs for this issue:

Affects: epel-all [bug 1517686]
Affects: fedora-all [bug 1517687]
Comment 2 Adam Mariš 2017-11-27 08:56:38 UTC 
Mitigation:

if you are running Exim 4.88 or newer, then in the main section of your Exim configuration, set:

chunking_advertise_hosts =

This disables advertising the ESMTP CHUNKING extension, making the BDAT verb unavailable and avoids letting an attacker apply the logic.
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