Cyber Resilience

CVE-2021-40084

CriticalPublic PoCRCE

Published: 25 August 2021

Published
25 August 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0150 81.5th percentile
Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-40084 is a critical-severity Code Injection (CWE-94) vulnerability in Artixlinux Opensysusers. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 18.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

opensysusers through 0.6 does not safely use eval on files in sysusers.d that may contain shell metacharacters. For example, it allows command execution via a crafted GECOS field whereas systemd-sysusers (a program with the same specification) does not do that.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

artixlinux
opensysusers
≤ 0.6

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Validates inputs used in dynamic code generation to block injected directives.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

References