CVE-2020-8794

Name: CVE-2020-8794
Creator: NVD / NIST
Published: 2020-02-25T17:15:13.197+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 88.53%

Last modified Jun 17, 2026

CVE-2020-8794 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. OpenSMTPD before 6.6.4 allows remote code execution because of an out-of-bounds read in mta_io in mta_session.c for multi-line replies. Although this vulnerability affects the client side of OpenSMTPD, it is possible to attack a server because the server code launches the client code during bounce handling.. EPSS estimates a 88.53% chance of exploitation in the next 30 days.

Description

OpenSMTPD before 6.6.4 allows remote code execution because of an out-of-bounds read in mta_io in mta_session.c for multi-line replies. Although this vulnerability affects the client side of OpenSMTPD, it is possible to attack a server because the server code launches the client code during bounce handling.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

88.53%

99.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions
Opensmtpd	Opensmtpd	< 6.6.4
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.10
Fedoraproject	Fedora	31
Fedoraproject	Fedora	32
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0

References

http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2020/Feb/32Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/02/26/1Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/1Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/2Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/04/7Exploit, Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OPH4QU4DNVHA7ACFXMYFCEP5PSXXPN4E/
https://usn.ubuntu.com/4294-1/Patch, Third Party Advisory
https://www.debian.org/security/2020/dsa-4634Third Party Advisory
https://www.openbsd.org/security.htmlThird Party Advisory
https://www.openwall.com/lists/oss-security/2020/02/24/5Exploit, Mailing List, Third Party Advisory
http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2020/Feb/32Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/02/26/1Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/1Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/2Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/04/7Exploit, Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OPH4QU4DNVHA7ACFXMYFCEP5PSXXPN4E/
https://usn.ubuntu.com/4294-1/Patch, Third Party Advisory
https://www.debian.org/security/2020/dsa-4634Third Party Advisory
https://www.openbsd.org/security.htmlThird Party Advisory
https://www.openwall.com/lists/oss-security/2020/02/24/5Exploit, Mailing List, Third Party Advisory

Timeline

Published: Feb 25, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8794?

How severe is CVE-2020-8794?

CVE-2020-8794 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 88.53% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8794?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8794?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST