Out-of-bounds read in OpenSMTPD - CVE-2020-8794

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Main Vulnerability Database Vulnerabilities #VU25625

Out-of-bounds read in OpenSMTPD - CVE-2020-8794

Published: February 26, 2020 / Updated: June 17, 2021


Vulnerability identifier: #VU25625
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-8794
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: Public exploit is available

Vulnerability details

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition in mta_io() function in mta_session.c for multi-line replies during mail delivery. A remote attacker can use a mail server to send specially crafted replies, trigger out-of-bounds read error and read contents of memory on the system.


Affected software

OpenSMTPD
Arch Linux
Fedora
opensmtpd (Ubuntu package)
opensmtpd (Debian package)
opensmtpd-extras (Alpine package)
libasr
opensmtpd

How to mitigate CVE-2020-8794

Install updates from vendor's website.

OpenSMTPD - update to 6.6.4p1
opensmtpd (Ubuntu package) - addressed in versions 6.0.3p1-1ubuntu0.2, 6.0.3p1-6ubuntu0.2
opensmtpd (Debian package) - addressed in versions 6.0.2p1-2+deb9u3, 6.0.3p1-5+deb10u4
opensmtpd-extras (Alpine package) - update to 6.7.1-r0
libasr - update to 1.0.4-2.el7
opensmtpd - addressed in versions 6.6.4p1-1.el8, 6.6.4p1-1.fc30, 6.6.4p1-1.fc31, 6.6.4p1-2.fc32, 6.6.4p1-3.el7

Links to Public Exploits and PoC-codes

External References

Related Security Bulletins