Ubuntu update for Exim

1) Use-after-free error

EUVDB-ID: #VU9427

Risk: High

CVSSv3.1: 8.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-16943

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists due to a use-after-free memory error in the ESMTP CHUNKING extension within the receive_msg() function in receive.c. A remote attacker can connect to the SMTP service, send a specially crafted BDAT command, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation

Update the affected packages

Ubuntu 17.10:

exim4-daemon-heavy 4.89-5ubuntu1.1

exim4-daemon-light 4.89-5ubuntu1.1

Ubuntu 17.04:

exim4-daemon-heavy 4.88-5ubuntu1.2

exim4-daemon-light 4.88-5ubuntu1.2

Vulnerable software versions

Ubuntu: 17.04 - 17.10

External links

http://www.ubuntu.com/usn/usn-3493-1/

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.