CVE-2021-46686

CVE-2021-46686 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Description

Improper neutralization of special elements used in an OS command ('OS Command Injection') issue exists in acmailer CGI ver.4.0.3 and earlier and acmailer DB ver.1.1.5 and earlier. If this vulnerability is exploited, an arbitrary OS command may be executed by an attacker.

Frequently asked questions

What is CVE-2021-46686?
Improper neutralization of special elements used in an OS command ('OS Command Injection') issue exists in acmailer CGI ver.4.0.3 and earlier and acmailer DB ver.1.1.5 and earlier. If this vulnerability is exploited, an arbitrary OS command may be executed by an attacker.
How severe is CVE-2021-46686?
CVE-2021-46686 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-46686 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2021-46686?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2021-46686 have an EU (EUVD) identifier?
Yes. CVE-2021-46686 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-4863.
When was CVE-2021-46686 published?
CVE-2021-46686 was published on 2025-02-18 and last updated on 2026-06-17.

References

Other CWE-78 (OS Command Injection) vulnerabilities

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