CVE-2020-8794

Exp

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.

Published: 2020-02-25 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-8794 is rated High Exploit Risk (90.2/100): CVSS Critical severity, with high exploitation likelihood (EPSS 88.14%, 99th percentile). 6 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.19% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2020-8794

EDB-ID Source Kind Published Link
48185 exploit_db edb 2020-03-09 Exploit-DB ↗
48140 exploit_db edb 2020-02-26 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-8794

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 86.94% 88.14% +1.19%
2 2025-12-27 88.14% 86.94% -1.19%
3 2025-11-21 — 88.14% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-8794

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
10.0 2.0 HIGH
AV:N/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 10.0 [email protected]

Weakness enumeration for CVE-2020-8794

OS Trackers for CVE-2020-8794

vendor priority summary link
alpine critical CVE-2020-8794: 2 source package rows (opensmtpd, opensmtpd-extras); 9 state rows across 8 repos (3.10-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.22-community, edge-community, edge-main); fixed 5, open 4. https://security.alpinelinux.org/vuln/CVE-2020-8794
debian not yet assigned CVE-2020-8794 not yet assigned priority: Debian including 1 source packages (opensmtpd), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-8794
ubuntu high CVE-2020-8794 high priority: Ubuntu including 1 source packages (opensmtpd), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 16, needed 1. https://ubuntu.com/security/CVE-2020-8794

Affected software / configurations for CVE-2020-8794

Vendor Product Version Raw CPE
opensmtpd opensmtpd < 6.6.4 cpe:2.3:a:opensmtpd:opensmtpd:*:*:*:*:*:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 19.10 cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
fedoraproject fedora 31 cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2020-8794

URL Tags
http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.html Exploit Third Party Advisory VDB Entry
http://seclists.org/fulldisclosure/2020/Feb/32 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/02/26/1 Exploit Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/1 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2020/03/01/2 Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/04/7 Exploit 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-4634 Third Party Advisory
https://www.openbsd.org/security.html Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/02/24/5 Exploit Mailing List Third Party Advisory
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