CVE & CISA-KEV Catalog

CVE-2020-8794

CRITICALEPSS 100th pctl
9.8
CVSS v3
NVD

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.

CWE-125Out-of-bounds Read

How to fix

Remediation Available
opensmtpdDebian
Fixed in:6.6.4p1-1CVE-2020-8794
Fixed in:6.6.4p1-1CVE-2020-8794
Fixed in:6.6.4p1-1CVE-2020-8794
Fixed in:6.6.4p1-1CVE-2020-8794
opensmtpdUbuntu
Fixed in:5.4.1p1-1ubuntu0.1~esm1USN-4875-1
Fixed in:5.7.3p2-1ubuntu0.1~esm2USN-4875-1
Fixed in:6.0.3p1-1ubuntu0.2USN-4294-1

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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

88.90%probability of exploitation in 30 days
100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

References

Other references1

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2014-0160High7.5100%KEVFix
CVE-2025-5777High7.5100%KEV + RansomFix
CVE-2021-4034High7.895%KEVFix
CVE-2023-49285High8.689%-Fix
CVE-2023-21769High7.589%-Fix
CVE-2026-3055Critical9.884%KEVFix

Common questions

How do I fix CVE-2020-8794?

Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2020-8794 being actively exploited?

Not that we know of. CVE-2020-8794 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 88.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 100% of all scored CVEs.

How severe is CVE-2020-8794?

CVE-2020-8794 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2020-8794 affect?

Published advisories record a fix for opensmtpd (Debian), opensmtpd (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.