CVE-2021-20617
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceImproper access control vulnerability in acmailer (versions 4.0.1 and earlier) and acmailer DB (versions 1.1.3 and earlier) allows unauthenticated remote attackers to bypass authentication mechanisms, execute arbitrary OS commands on the server, and elevate privileges to administrator level, potentially exposing sensitive data.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 4.0.1<= 1.1.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify acmailer installationLocate the acmailer installation directory and check for version.php, VERSION file, or similar version marker files. Alternatively, check the login page source or admin interface footer for version information.Affected if The detected version is 4.0.1 or earlier, or the version cannot be determined but the product appears to be acmailer.
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Identify acmailer DB installationLocate the acmailer DB installation directory and check for version.php, VERSION file, or admin interface for version information.Affected if The detected version is 1.1.3 or earlier, or the version cannot be determined but the product appears to be acmailer DB.
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Verify authentication configurationReview the authentication configuration files in the acmailer installation, typically found in config directories. Check for settings related to authentication bypass, session management, or password verification.Affected if Authentication is not properly enforced, or configuration files show weak or missing authentication controls.
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Check for unauthorized admin accountsQuery the user database or user configuration files for unexpected administrator-level accounts, particularly those created without your knowledge or outside normal registration workflows.Affected if Unexpected administrator accounts exist in the system, especially accounts with no associated registration history.
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Inspect for command execution artifactsReview web server logs, shell history files, and any unexpected scripts or executables in the web root or system directories. Look for suspicious GET/POST requests to unfamiliar endpoints.Affected if Evidence of arbitrary command execution exists, such as suspicious processes, unexpected files, or anomalous web requests.
You are affected if acmailer version is 4.0.1 or earlier, or acmailer DB version is 1.1.3 or earlier, or if evidence of unauthorized access or command execution is found in logs or the system.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpdate acmailer to version 4.0.2 or later and acmailer DB to version 1.1.4 or later. Conduct a full security assessment to determine if the server has been compromised, as CVSS 9.8 indicates likely active exploitation of this critical flaw.
Acmailer 4.0.2 or later; Acmailer Db 1.1.4 or later
- 1. Backup the current acmailer installation and database before proceeding with any upgrade.
- 2. Download the latest version of Acmailer from the official vendor website (www.acmailer.jp).
- 3. Download the latest version of Acmailer Db from the official vendor website.
- 4. Replace the existing Acmailer files with the new version, preserving configuration files if required.
- 5. Replace the existing Acmailer Db files with the new version, preserving configuration files if required.
- 6. Verify the upgrade by logging into the administrative interface.
- 7. Test that normal functionality (sending emails, managing contacts) works correctly after the upgrade.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20617 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20617 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data