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 services: Not assessed

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
9.8CRITICALmedium confidence
EG Risk
84
EG Risk 84/100CISA SSVC

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%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
89%
EPSS %ILE
99th
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: weaponized) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

February 25, 2020

Last Modified

November 21, 2024

Advisory Details (9)

Auto-updated Oct 4, 2026
🔬 Proof of concept available. Patch available.
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

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / 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 rangeFix by version rangeDependents
opensmtpd6.0.3p1-5, 6.0.3p1-5+deb10u1, 6.0.3p1-5+deb10u2, 6.0.3p1-5+deb10u3
  • every version up to 6.0.3p1-5+deb10u4: fixed in 6.0.3p1-5+deb10u4
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
opensmtpd—
  • every version up to 6.6.4p1-1: fixed in 6.6.4p1-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
opensmtpd—
  • every version up to 6.6.4p1-1: fixed in 6.6.4p1-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
opensmtpd—
  • every version up to 6.6.4p1-1: fixed in 6.6.4p1-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
opensmtpd—
  • every version up to 6.6.4p1-1: fixed in 6.6.4p1-1
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
opensmtpd6.0.2p1-2, 6.0.2p1-2+deb9u1, 6.0.2p1-2+deb9u2
  • every version up to 6.0.2p1-2+deb9u3: fixed in 6.0.2p1-2+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 2× 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. 2026-09-30 15:25 UTCEG score recompute
  2. 2026-09-30 14:59 UTCEPSS rescore
  3. 2026-09-27 09:32 UTCOSV refresh
  4. 2026-09-26 15:54 UTCEPSS rescore
  5. 2026-09-26 15:54 UTCEPSS rescore
  6. 2026-09-26 00:21 UTCEPSS rescore
  7. 2026-09-24 14:00 UTCEPSS rescore
  8. 2026-09-22 14:44 UTCEPSS rescore
  9. 2026-09-21 20:28 UTCEPSS rescore
  10. 2026-09-19 15:37 UTCEPSS rescore
  11. 2026-09-17 19:22 UTCEPSS rescore
  12. 2026-09-07 18:51 UTCOSV refresh
  13. 2026-09-06 13:44 UTCEPSS rescore
  14. 2026-09-05 15:25 UTCEPSS rescore
  15. 2026-09-01 03:32 UTCEPSS rescore
  16. 2026-08-30 19:14 UTCEPSS rescore
  17. 2026-08-28 21:37 UTCEPSS rescore
  18. 2026-08-26 14:42 UTCEPSS rescore
  19. 2026-08-21 23:45 UTCEPSS rescore
  20. 2026-08-21 04:14 UTCOSV refresh
  21. 2026-08-19 17:00 UTCEPSS rescore
  22. 2026-08-17 13:43 UTCEPSS rescore
  23. 2026-08-17 13:43 UTCEPSS rescore
  24. 2026-08-16 14:52 UTCEPSS rescore
  25. 2026-08-13 21:57 UTCEPSS rescore
Show 52 more
  1. 2026-08-08 16:33 UTCEPSS rescore
  2. 2026-08-07 16:23 UTCEPSS rescore
  3. 2026-08-05 19:40 UTCOSV refresh
  4. 2026-07-30 01:27 UTCEPSS rescore
  5. 2026-07-25 14:15 UTCEPSS rescore
  6. 2026-07-24 14:15 UTCEPSS rescore
  7. 2026-07-23 01:55 UTCEG score recompute
  8. 2026-07-22 22:41 UTCEG score recompute
  9. 2026-07-22 14:05 UTCEPSS rescore
  10. 2026-07-21 15:22 UTCEPSS rescore
  11. 2026-07-21 15:22 UTCEPSS rescore
  12. 2026-07-19 18:48 UTCOSV refresh
  13. 2026-07-15 16:55 UTCEPSS rescore
  14. 2026-07-15 16:55 UTCEPSS rescore
  15. 2026-07-11 08:25 UTCEPSS rescore
  16. 2026-07-11 08:25 UTCEPSS rescore
  17. 2026-07-06 16:25 UTCEPSS rescore
  18. 2026-07-02 08:17 UTCOSV refresh
  19. 2026-07-01 15:03 UTCEPSS rescore
  20. 2026-06-28 04:54 UTCEPSS rescore
  21. 2026-06-28 04:54 UTCEPSS rescore
  22. 2026-06-24 14:03 UTCEPSS rescore
  23. 2026-06-24 14:03 UTCEPSS rescore
  24. 2026-06-23 21:31 UTCEPSS rescore
  25. 2026-06-23 21:31 UTCEPSS rescore
  26. 2026-06-22 14:23 UTCEPSS rescore
  27. 2026-06-17 17:50 UTCEPSS rescore
  28. 2026-06-15 17:46 UTCEPSS rescore
  29. 2026-06-14 23:15 UTCEPSS rescore
  30. 2026-06-14 08:13 UTCOSV refresh
  31. 2026-06-12 23:10 UTCEPSS rescore
  32. 2026-06-12 23:10 UTCEPSS rescore
  33. 2026-06-10 22:16 UTCEPSS rescore
  34. 2026-06-10 13:20 UTCEPSS rescore
  35. 2026-06-07 15:23 UTCEPSS rescore
  36. 2026-06-07 15:23 UTCEPSS rescore
  37. 2026-06-05 22:45 UTCEPSS rescore
  38. 2026-06-05 22:45 UTCEPSS rescore
  39. 2026-06-05 06:08 UTCEPSS rescore
  40. 2026-06-05 06:08 UTCEPSS rescore
  41. 2026-06-01 13:50 UTCEPSS rescore
  42. 2026-05-29 13:42 UTCEPSS rescore
  43. 2026-05-28 13:43 UTCEPSS rescore
  44. 2026-05-28 13:43 UTCEPSS rescore
  45. 2026-05-27 07:17 UTCEG score recompute
  46. 2026-05-27 07:17 UTCVendor advisory
  47. 2026-05-27 07:17 UTCGHSA enrichment
  48. 2026-05-26 13:42 UTCEPSS rescore
  49. 2026-05-26 13:42 UTCEPSS rescore
  50. 2026-05-26 08:16 UTCOSV refresh
  51. 2026-05-26 07:17 UTCEPSS rescore
  52. 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 ↗
  • Metasploitexploit/unix/local/opensmtpd_oob_read_lpe✓ verified
    First seen Feb 24, 2020

    OpenSMTPD OOB Read Local Privilege Escalation

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

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

    Open source ↗

Related CVEs(same product + same vendor + same CWE)

Same vendor

2 shown

ubuntu:USN-4294-1 · ubuntu:USN-4875-1

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 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. EchelonGraph's EG-KEV model classifies it as weaponized: a functional public exploit exists. FIRST EPSS estimates a 89% probability of exploitation in the next 30 days (99th percentile of EPSS-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?
A fix for CVE-2020-8794 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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