Integer overflow in Exim - CVE-2020-28020

Vulnerability identifier: #VU52864

CSH Severity: High

CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2020-28020

CWE-ID: CWE-190

Exploitation vector: Remote access

Exploit availability: No public exploit available

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

The vulnerability exists due to integer overflow in receive_msg() function. A remote non-authenticated attacker can send specially crafted data to the mail server, trigger integer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Exim
Gentoo Linux
Ubuntu
exim4-base (Ubuntu package)
exim4-daemon-heavy (Ubuntu package)
exim4-daemon-light (Ubuntu package)

Install updates from vendor's website.

Exim - update to 4.94.2
exim4-base (Ubuntu package) - addressed in versions 4.86.22ubuntu2.6+esm1, 4.90.1-1ubuntu1.8, 4.93-13ubuntu1.5, 4.94-7ubuntu1.2, 4.94-15ubuntu1.2
exim4-daemon-heavy (Ubuntu package) - addressed in versions 4.86.22ubuntu2.6+esm1, 4.90.1-1ubuntu1.8, 4.93-13ubuntu1.5, 4.94-7ubuntu1.2, 4.94-15ubuntu1.2
exim4-daemon-light (Ubuntu package) - addressed in versions 4.86.22ubuntu2.6+esm1, 4.90.1-1ubuntu1.8, 4.93-13ubuntu1.5, 4.94-7ubuntu1.2, 4.94-15ubuntu1.2

• http://seclists.org/oss-sec/2021/q2/91

• Multiple vulnerabilities in Exim
• Gentoo update for Exim
• Ubuntu update for exim4
• Ubuntu update for exim4