Security readout for executives and security teams
Plain-English summary
acmailer CGI and acmailer DB contain a critical command injection flaw. A remote unauthenticated attacker may be able to make the server run arbitrary operating system commands, which can lead to full compromise of the web host and hosted data.
Executive priority
Treat this as urgent for any affected internet-facing acmailer deployment. The impact is potentially full server compromise, but prioritization should start with confirming whether the products exist in the environment.
Technical view
CVE-2021-46686 is CWE-78 OS command injection in acmailer CGI 4.0.3 and earlier and acmailer DB 1.1.5 and earlier. The CVSS 3.0 score is 9.8, with network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is limited to organizations running affected Extra Innovation acmailer products, especially internet-facing CGI or webmail/contact-form deployments. The source bundle does not provide CPEs, deployment prevalence, or exact vulnerable endpoints.
Exploitation context
The supplied sources support remote, unauthenticated command execution risk. They do not show confirmed active exploitation, and the bundle marks KEV as false. Public exploit availability is not established from the provided evidence.
Researcher notes
The public bundle establishes product names, affected version ceilings, CWE-78, and CVSS severity. It does not include exploit details, IOCs, patch version names, CPEs, or proof of exploitation, so validation should stay product-and-version focused.
Mitigation direction
- Inventory acmailer CGI and acmailer DB deployments and versions.
- Check Extra Innovation and JVN advisories for supported update or replacement guidance.
- Remove public exposure for affected instances until vendor guidance is applied.
- Restrict access to trusted networks where the service must remain available.
- Review web server and application logs for suspicious command execution indicators.
Validation and detection
- Confirm whether acmailer CGI 4.0.3 or earlier is installed.
- Confirm whether acmailer DB 1.1.5 or earlier is installed.
- Identify internet-facing hosts running acmailer components.
- Verify remediation against vendor or JVN advisory guidance.
- Check logs around CGI requests for anomalous activity.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-78: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-46686 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
9.8CriticalVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://acmailer.jp/info/de.cgi?id=103CVE reference
- https://www.acmailer.jp/info/de.cgi?id=102CVE reference
- https://jvn.jp/en/jp/JVN96957439/CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.