Debian Security Advisory

DSA-4053-1 exim4 -- security update

Date Reported:
30 Nov 2017
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 882648, Bug 882671.
In Mitre's CVE dictionary: CVE-2017-16943, CVE-2017-16944.
More information:

Several vulnerabilities have been discovered in Exim, a mail transport agent. The Common Vulnerabilities and Exposures project identifies the following issues:

  • CVE-2017-16943

    A use-after-free vulnerability was discovered in Exim's routines responsible for parsing mail headers. A remote attacker can take advantage of this flaw to cause Exim to crash, resulting in a denial of service, or potentially for remote code execution.

  • CVE-2017-16944

    It was discovered that Exim does not properly handle BDAT data headers allowing a remote attacker to cause Exim to crash, resulting in a denial of service.

For the stable distribution (stretch), these problems have been fixed in version 4.89-2+deb9u2. Default installations disable advertising the ESMTP CHUNKING extension and are not affected by these issues.

We recommend that you upgrade your exim4 packages.

For the detailed security status of exim4 please refer to its security tracker page at: