CVE-2020-7247: OpenSMTPD Remote Code Execution Vulnerability

Vulnerability summary

CVE-2020-7247 is a high (CVSS 10.0) OS Command Injection vulnerability in OpenBSD OpenSMTPD. It is known to be exploited: CISA lists it, first on 25-03-2022. EPSS estimates a 98.97% chance of exploitation in the next 30 days, higher than 99.9% of scored vulnerabilities. 10 public exploits are recorded.

Timeline

1. 29-01-2020
   PublishedVulnerability first disclosed.
2. 25-03-2022
   Added to CISA KEVOpenSMTPD Remote Code Execution Vulnerability
3. 15-04-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

Description

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.

• CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
• CWE-755Improper Handling of Exceptional ConditionsThe product does not handle or incorrectly handles an exceptional condition.