CVE-2021-20617Public exploitNetwork attack vector

Unauthenticated command execution via unquoted sendmail path

Published Jan 14, 2021 · Updated Aug 3, 2024

OS command injection in acmailer 4.0.1 and earlier and acmailer DB 1.1.3 and earlier allows remote attackers to execute commands. The init_ctl.cgi handler interpolates the untrusted sendmail_path POST parameter directly into an operating-system command. No authentication is required while init_ctl.cgi remains deployed, allowing compromise of the host under the CGI process privileges.

CVSS severity9.8
Critical
EPSS probability7.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in acmailer 4.0.1 and earlier and acmailer DB 1.1.3 and earlier allows remote attackers to execute commands. The init_ctl.cgi handler interpolates the untrusted sendmail_path POST parameter directly into an operating-system command. No authentication is required while init_ctl.cgi remains deployed, allowing compromise of the host under the CGI process privileges.

The record

CVE
CVE-2021-20617
Published
Jan 14, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284, T1059.004, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:C/I:C/A:C
7.5Japan Vulnerability NotesAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8Japan Vulnerability NotesCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1059.004Unix Shell
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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