CVE-2021-20617: Improper access control vulnerability in acmailer ver

Q: How do I fix CVE-2021-20617?

acmailer: upgrade to newer than 4.0.1; acmailer db: upgrade to newer than 1.1.3. Exact commands for each OS are on this page.

Q: Is CVE-2021-20617 being exploited?

CVE-2021-20617 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-20617 affect?

CVE-2021-20617 affects acmailer, acmailer db. Severity is critical (CVSS 9.8). Improper access control vulnerability in acmailer ver. 4.0.1 and earlier, and acmailer DB ver. 1.1.3 and earlier allows remote attackers to execute an arbitrary OS command, or gain an administrative privilege which may result in obtaining t

Q: How urgent is CVE-2021-20617?

Priority 63/100. Critical severity; EPSS top 6%: very likely to be exploited; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADEUPGRADE

CVE-2021-20617 is a critical-severity flaw (CVSS 9.8) affecting acmailer, acmailer db. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper access control vulnerability in acmailer ver. 4.0.1 and earlier, and acmailer DB ver. 1.1.3 and earlier allows remote attackers to execute an arbitrary OS command, or gain an administrative privilege which may result in obtaining the sensitive information on the server via unspecified vectors.

Why this priority

Critical severity
EPSS top 6%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	7.4% (top 6%)
CISA exploited list	No
Published	2021-01-14
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: acmailer

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-01-14 09:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

acmailer acmailer UPGRADE

Affected: <= 4.0.1

Fixed in: newer than 4.0.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy acmailer || rpm -q acmailer || acmailer --version

2. UPGRADE to newer than 4.0.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade acmailer

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade acmailer

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

acmailer acmailer db UPGRADE

Affected: <= 1.1.3

Fixed in: newer than 1.1.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy acmailer-db || rpm -q acmailer-db || acmailer-db --version

2. UPGRADE to newer than 1.1.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade acmailer-db

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade acmailer-db

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: Acmailer - Improper Access Control to OS Command Injection

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-20617?

acmailer: upgrade to newer than 4.0.1; acmailer db: upgrade to newer than 1.1.3. Exact commands for each OS are on this page.

Is CVE-2021-20617 being exploited?

CVE-2021-20617 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-20617 affect?

CVE-2021-20617 affects acmailer, acmailer db. Severity is critical (CVSS 9.8). Improper access control vulnerability in acmailer ver. 4.0.1 and earlier, and acmailer DB ver. 1.1.3 and earlier allows remote attackers to execute an arbitrary OS command, or gain an administrative privilege which may result in obtaining t

How urgent is CVE-2021-20617?

Priority 63/100. Critical severity; EPSS top 6%: very likely to be exploited; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-20618 CRITICAL 9.8 UPGRADE UPGRADE Privilege chaining vulnerability in acmailer ver
CVE-2016-1142 CRITICAL 9.1 UPGRADE Seeds acmailer before 3.8.21 and 3.9.x before 3.9.15 Beta allows remote authenticated users to execute arbitra
CVE-2015-2971 MEDIUM 5.5 UPGRADE Directory traversal vulnerability in Seeds acmailer before 3.8.18 and 3.9.x before 3.9.12 Beta allows remote a
CVE-2014-3896 MEDIUM 6.8 UPGRADE Multiple cross-site request forgery (CSRF) vulnerabilities in CGI programs in Seeds acmailer before 3.8.17 and

References

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