CVE-2017-16943

Publication date 27 November 2017

Last updated 25 August 2025

Ubuntu priority

High

Why this priority?

Cvss 3 Severity Score

9.8 · Critical

Score breakdown

Description

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.

Read the notes from the security team

Status

Package Ubuntu Release Status
exim4 17.10 artful
Fixed 4.89-5ubuntu1.1
17.04 zesty
Fixed 4.88-5ubuntu1.2
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected

Notes

mdeslaur

only affects Exim 4.88 or newer in zesty, the 78_Disable-chunking-BDAT-by-default.patch patch sets chunking_advertise_hosts = by default, which disables the security issue unless the local configurations changed the default value. Probably no code execution in Ubuntu because the exim binary is built with PIE

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
exim4

Severity score breakdown

Parameter Value
Base score 9.8 · Critical
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

Other references