CVE-2020-8794

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Weaponized
9.8EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 89%
  • Public exploit code is available (Metasploit, Exploit-DB (verified), epss top5pct, epss high, public exploit)
CISA-KEV: Not listedEPSS PROB: 89%CVSS: 9.8Exploit: Metasploit · Exploit-DB (verified) · epss top5pct · epss high · public exploitExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
84(Track*)
EG Risk 84/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation89% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
89%
EPSS %ILE
100%
KEV
Not listed

Published

February 25, 2020

Last Modified

November 21, 2024

Advisory Details (9)

Auto-updated Aug 15, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

OpenBSD: Security

https://www.openbsd.org/security.html
generic

[SECURITY] [DSA 4634-1] opensmtpd security update

https://www.debian.org/security/2020/dsa-4634
generic

[SECURITY] Fedora 32 Update: opensmtpd-6.6.4p1-2.fc32 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OPH4QU4DNVHA7ACFXMYFCEP5PSXXPN4E/
generic🟡 PoC Available

oss-security - 21Nails: Multiple vulnerabilities in Exim

http://www.openwall.com/lists/oss-security/2021/05/04/7
generic

oss-security - Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)

http://www.openwall.com/lists/oss-security/2020/03/01/2
generic

oss-security - Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)

http://www.openwall.com/lists/oss-security/2020/03/01/1
generic

oss-security - Re: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)

http://www.openwall.com/lists/oss-security/2020/02/26/1
generic

Full Disclosure: LPE and RCE in OpenSMTPD's default install (CVE-2020-8794)

http://seclists.org/fulldisclosure/2020/Feb/32
generic

Packet Storm Security

http://packetstormsecurity.com/files/156633/OpenSMTPD-Out-Of-Bounds-Read-Local-Privilege-Escalation.html

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuopensmtpd (6.0.3p1-6ubuntu0.2) @ eoan2026-05-27ubuntu
ubuntuopensmtpd (5.7.3p2-1ubuntu0.1~esm2) @ xenial2026-05-27ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(6 across 6 ecosystems)
Debian:10(1)
PackageVulnerable rangeFixed inDependents
opensmtpd6.0.3p1-5, 6.0.3p1-5+deb10u1, 6.0.3p1-5+deb10u2, 6.0.3p1-5+deb10u36.0.3p1-5+deb10u4—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
opensmtpd—6.6.4p1-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
opensmtpd—6.6.4p1-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
opensmtpd—6.6.4p1-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
opensmtpd—6.6.4p1-1—
Debian:9(1)
PackageVulnerable rangeFixed inDependents
opensmtpd6.0.2p1-2, 6.0.2p1-2+deb9u1, 6.0.2p1-2+deb9u26.0.2p1-2+deb9u3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 5× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-21 04:14 UTCOSV refresh
  2. 2026-08-19 17:00 UTCEPSS rescore
  3. 2026-08-17 13:43 UTCEPSS rescore
  4. 2026-08-17 13:43 UTCEPSS rescore
  5. 2026-08-16 14:52 UTCEPSS rescore
  6. 2026-08-13 21:57 UTCEPSS rescore
  7. 2026-08-08 16:33 UTCEPSS rescore
  8. 2026-08-07 16:23 UTCEPSS rescore
  9. 2026-08-05 19:40 UTCOSV refresh
  10. 2026-07-30 01:27 UTCEPSS rescore
  11. 2026-07-25 14:15 UTCEPSS rescore
  12. 2026-07-24 14:15 UTCEPSS rescore
  13. 2026-07-23 01:55 UTCEG score recompute
  14. 2026-07-22 22:41 UTCEG score recompute
  15. 2026-07-22 14:05 UTCEPSS rescore
  16. 2026-07-21 15:22 UTCEPSS rescore
  17. 2026-07-21 15:22 UTCEPSS rescore
  18. 2026-07-19 18:48 UTCOSV refresh
  19. 2026-07-15 16:55 UTCEPSS rescore
  20. 2026-07-15 16:55 UTCEPSS rescore
  21. 2026-07-11 08:25 UTCEPSS rescore
  22. 2026-07-11 08:25 UTCEPSS rescore
  23. 2026-07-06 16:25 UTCEPSS rescore
  24. 2026-07-02 08:17 UTCOSV refresh
  25. 2026-07-01 15:03 UTCEPSS rescore
Show 33 more
  1. 2026-06-28 04:54 UTCEPSS rescore
  2. 2026-06-28 04:54 UTCEPSS rescore
  3. 2026-06-24 14:03 UTCEPSS rescore
  4. 2026-06-24 14:03 UTCEPSS rescore
  5. 2026-06-23 21:31 UTCEPSS rescore
  6. 2026-06-23 21:31 UTCEPSS rescore
  7. 2026-06-22 14:23 UTCEPSS rescore
  8. 2026-06-17 17:50 UTCEPSS rescore
  9. 2026-06-15 17:46 UTCEPSS rescore
  10. 2026-06-14 23:15 UTCEPSS rescore
  11. 2026-06-14 08:13 UTCOSV refresh
  12. 2026-06-12 23:10 UTCEPSS rescore
  13. 2026-06-12 23:10 UTCEPSS rescore
  14. 2026-06-10 22:16 UTCEPSS rescore
  15. 2026-06-10 13:20 UTCEPSS rescore
  16. 2026-06-07 15:23 UTCEPSS rescore
  17. 2026-06-07 15:23 UTCEPSS rescore
  18. 2026-06-05 22:45 UTCEPSS rescore
  19. 2026-06-05 22:45 UTCEPSS rescore
  20. 2026-06-05 06:08 UTCEPSS rescore
  21. 2026-06-05 06:08 UTCEPSS rescore
  22. 2026-06-01 13:50 UTCEPSS rescore
  23. 2026-05-29 13:42 UTCEPSS rescore
  24. 2026-05-28 13:43 UTCEPSS rescore
  25. 2026-05-28 13:43 UTCEPSS rescore
  26. 2026-05-27 07:17 UTCEG score recompute
  27. 2026-05-27 07:17 UTCVendor advisory
  28. 2026-05-27 07:17 UTCGHSA enrichment
  29. 2026-05-26 13:42 UTCEPSS rescore
  30. 2026-05-26 13:42 UTCEPSS rescore
  31. 2026-05-26 08:16 UTCOSV refresh
  32. 2026-05-26 07:17 UTCEPSS rescore
  33. 2026-05-26 07:17 UTCEPSS rescore

Publicly available exploits

(3 references)

Working exploit code is in the public domain (1 Metasploit module) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-48185✓ verified
    First seen Mar 9, 2020

    OpenSMTPD - OOB Read Local Privilege Escalation (Metasploit)

    Open source ↗
  • Exploit-DBEDB-48140
    First seen Feb 26, 2020

    OpenSMTPD < 6.6.3p1 - Local Privilege Escalation + Remote Code Execution

    Open source ↗
  • Metasploitexploit/unix/local/opensmtpd_oob_read_lpe✓ verified
    First seen Feb 24, 2020

    OpenSMTPD OOB Read Local Privilege Escalation

    Open source ↗

Frequently asked(5)

What is CVE-2020-8794?
CVE-2020-8794 is a critical vulnerability published on February 25, 2020. OpenSMTPD before 6.6.4 allows remote code execution because of an out-of-bounds read in mtaio in mtasession.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…
When was CVE-2020-8794 disclosed?
CVE-2020-8794 was first published in the National Vulnerability Database on February 25, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-8794 actively exploited?
CVE-2020-8794 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89% probability of exploitation in the next 30 days, which ranks it in the top 0.2% of all scored CVEs.
What is the CVSS score of CVE-2020-8794?
CVE-2020-8794 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-8794?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-8794, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-8794

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