OpenSMTPD before 6.6.4 allows remote code execution because of an out-of-bounds read in…
Priority HIGH 84CWE-125Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
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.
Why it matters now
EPSS 0.889 99th percentileScored 2026-11-07
Public exploit Yes 4 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:opensmtpd:opensmtpd:*:*:*:*:*:*:*:* | before 6.6.4 | Vulnerable | Opensmtpd |
| cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* | 18.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:* | 19.10 | Vulnerable | Canonical |
| cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* | 31 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* | 32 | Vulnerable | Fedoraproject |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
- cpe:2.3:a:opensmtpd:opensmtpd:*:*:*:*:*:*:*:* Versions before 6.6.4 Vulnerable ·Opensmtpd
- cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* Versions 18.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:* Versions 19.10 Vulnerable ·Canonical
- cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* Versions 31 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2020-8794
- 2026-10-03 Alias added: GHSA-hmw3-c3g9-px9f
References
Exploit 4
- https://www.openwall.com/lists/oss-security/2020/02/24/5
- [oss-security] 20200226 Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)
- http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.html
- [oss-security] 20210504 21Nails: Multiple vulnerabilities in Exim
Patch 1
Advisory 6
- https://www.openbsd.org/security.html
- DSA-4634
- 20200227 LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)
- [oss-security] 20200301 Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)
- [oss-security] 20200301 Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)
- FEDORA-2020-b92d7083ca
Sources
- CVE-2020-8794 · CVE Program
- CVE-2020-8794 · NVD
- FIRST EPSS
- GHSA-hmw3-c3g9-px9f · GitHub Advisory Database · CC BY 4.0
- CVE-2020-8794 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences