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CVE-2020-7247

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in OpenBSD OpenSMTPD. For every flaw being used in attacks, see Exploited flaws.

CVE-2020-7247 is a security flaw in OpenBSD OpenSMTPD. Attackers can run their own code on OpenBSD OpenSMTPD. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Mar 2022.[1]

OpenBSD OpenSMTPD is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. OpenBSD has published a fix or advice.

Description

CISA calls it a remote code execution in OpenBSD OpenSMTPD. In its words: “smtp_mailaddr in smtp_session.c in OpenSMTPD, as used in OpenBSD and other products, allows remote attackers to execute arbitrary commands as root via a crafted SMTP session.”[1]

The CVE record adds: “smtp_mailaddr in smtp_session.c in OpenSMTPD 6.6, as used in OpenBSD 6.6 and other products, allows remote attackers to execute arbitrary commands as root via a crafted SMTP session, as demonstrated by shell metacharacters in a MAIL FROM field. This affects the "uncommented" default configuration. The issue exists because of an incorrect return value upon failure of input validation.”[2]

The underlying weakness is CWE-755, OS command injection (CWE-78), in MITRE’s list of common software weaknesses.

It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; OpenBSD’s advisory has them[3]. CISA names the product as OpenBSD OpenSMTPD.

Most families won’t have OpenBSD OpenSMTPD; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 25 Mar 2022, 786 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 15 Apr 2022 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 99%. That’s in the top 1% of the flaws it scores.[4]

CISA assesses it as automatable: attackers can run it against many targets at once.

CISA doesn’t say who was attacked, or how.

Fix

OpenBSD has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]

  1. Check whether you use it.OpenBSD OpenSMTPD is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 15 Apr 2022 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 99%.[4]

See also

Similar flaws

  • CVE-2022-44698, Microsoft Defender: smartScreen security feature bypass ·

Added the same day

  • CVE-2022-26318, WatchGuard Firebox and XTM Appliances: arbitrary code execution ·
  • CVE-2022-26143, Mitel MiCollab, MiVoice Business Express: access control ·
  • CVE-2022-21999, Microsoft Windows: print spooler privilege escalation ·
  • CVE-2021-42237, Sitecore XP: remote command execution ·
  • CVE-2021-22941, Citrix ShareFile: improper access control ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “OpenSMTPD Remote Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Mar 2022.
  2. ^ National Institute of Standards and Technology. “CVE-2020-7247 Detail”. National Vulnerability Database, published 29 Jan 2020.
  3. ^ OpenBSD. Advisories and fixes: openbsd.org.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.990, percentile 99.9, 31 Oct 2026.
  5. CVE Program. “CVE-2020-7247”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.