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Fencer Vulns
critical 9.8

CVE-2020-8794 in the critical feed json

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.

published 2020-02-25 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29642

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
88.9%
EPSS 88.9% chance of exploitation in 30 days, percentile 99.7%
public exploits
3
Metasploit, Exploit-DB

Summary

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.

Patch / fix

  • opensmtpd opensmtpd 6.6.4
  • opensmtpd Debian 14, Debian 13, Debian 12 6.6.4p1-1

debian advisories DEBIAN-CVE-2020-8794

  • opensmtpd Ubuntu 18.04 LTS 6.0.3p1-1ubuntu0.2
  • opensmtpd Ubuntu 20.04 LTS 6.6.4p1-1
  • opensmtpd Ubuntu Pro 16.04 LTS 5.7.3p2-1ubuntu0.1~esm2

ubuntu advisories UBUNTU-CVE-2020-8794

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • opensmtpd-extras Alpine 3.20, Alpine 3.19, Alpine 3.18 +5 more 6.6.4-r0

alpine advisories ALPINE-CVE-2020-8794

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • opensmtpd Arch Linux 6.6.4p1-1

arch linux advisories AVG-1105

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8794 updated cvss 8.3

opensmtpd: An out-of-bounds read could lead to remote code execution

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (Metasploit exploit/unix/local/opensmtpd_oob_read_lpe)
  2. Published

Exploit prediction

88.90% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Metasploit exploit/unix/local/opensmtpd_oob_read_lpe OpenSMTPD OOB Read Local Privilege Escalation metasploit exploit, average rank, 2020-02-24
  • EDB-48185 OpenSMTPD - OOB Read Local Privilege Escalation (Metasploit) local, 2020-03-09
  • EDB-48140 OpenSMTPD < 6.6.3p1 - Local Privilege Escalation + Remote Code Execution remote, 2020-02-26
  • openwall.com https://www.openwall.com/lists/oss-security/2020/02/24/5 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2020/02/26/1 referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.html referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2021/05/04/7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness

References

Sources

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