Security readout for executives and security teams
Plain-English summary
opensysusers through version 0.6 can mishandle system user definition files. If a malicious or untrusted sysusers.d entry is processed, shell metacharacters in fields such as GECOS may be evaluated, allowing command execution.
Executive priority
Treat this as a targeted hardening issue unless opensysusers is widely deployed in your Linux fleet. Prioritize systems where package pipelines, images, or automation can introduce sysusers.d files.
Technical view
The CVE describes unsafe use of eval while parsing sysusers.d files in opensysusers through 0.6. A crafted field can trigger command execution, unlike systemd-sysusers handling of the same specification. Source details do not provide CVSS, CWE, or a confirmed fixed version.
Likely exposure
Exposure is most likely on Linux systems using opensysusers through 0.6, especially where sysusers.d content can come from packages, automation, images, or other semi-trusted sources.
Exploitation context
No source in the bundle states active exploitation, and the CVE is not listed as KEV. Practical risk depends on an attacker influencing sysusers.d content that opensysusers later processes.
Researcher notes
The key issue is unsafe eval during sysusers.d parsing, with command execution possible via crafted metadata fields. Public data in the bundle is limited: no CVSS, CWE, confirmed exploit activity, or explicit fix version is provided.
Mitigation direction
- Check vendor or distribution guidance for fixed opensysusers packages.
- Upgrade opensysusers if your vendor identifies a corrected release.
- Restrict write access to sysusers.d directories and package build inputs.
- Review sysusers.d entries from third-party or automation-managed sources.
- Consider systemd-sysusers behavior where appropriate and vendor-supported.
Validation and detection
- Inventory systems using opensysusers and identify versions through 0.6.
- Confirm whether sysusers.d files are locally controlled or supplied by packages.
- Review package changelogs and Debian bug 992058 for remediation status.
- Audit recent sysusers.d changes for unexpected metacharacters or untrusted fields.
- Verify operational tooling does not generate sysusers.d content from untrusted input.
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.
CVE-2021-40084 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugs.debian.org/992058CVE reference · x_refsource_MISC
- https://github.com/artix-linux/opensysusers/releasesCVE reference · x_refsource_MISC
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.