Security readout for executives and security teams
Plain-English summary
CVE-2021-45707 affects the Rust nix crate. A specific group-list lookup can write outside its intended memory when a user belongs to more than 16 /etc/groups groups. Business risk depends on whether products use affected nix versions and call this function with local group data.
Executive priority
Treat as a targeted dependency remediation item, not an emergency based on current evidence. Prioritize inventory and upgrade where affected Rust services handle local identity or group information, especially in privileged or security-sensitive contexts.
Technical view
Affected nix versions are 0.16.0 through before 0.20.2, 0.21.x before 0.21.2, and 0.22.x before 0.22.2. The vulnerable API is unistd::getgrouplist, which can trigger an out-of-bounds write when handling users in more than 16 /etc/groups groups.
Likely exposure
Exposure is most likely in Rust applications or services that depend directly or transitively on affected nix versions and use unistd::getgrouplist. The triggering condition requires local group data where a queried user has more than 16 /etc/groups memberships.
Exploitation context
The provided sources do not cite active exploitation, and this CVE is not marked KEV. The sources describe the flaw condition, but do not provide CVSS, CWE, exploit prevalence, or confirmed real-world abuse evidence.
Researcher notes
Evidence is narrow but clear: the affected API, version ranges, and trigger condition are documented. Impact beyond an out-of-bounds write is not established in the provided sources, so avoid assuming code execution or privilege escalation without additional vendor evidence.
Mitigation direction
- Upgrade nix to a patched release: 0.20.2, 0.21.2, 0.22.2, or later.
- Review vendor or RustSec guidance before choosing an upgrade path.
- Rebuild affected Rust applications after dependency updates.
- Prioritize systems where local group membership data is attacker-influenced or externally provisioned.
Validation and detection
- Check Cargo.lock, SBOMs, and dependency manifests for affected nix versions.
- Identify direct or transitive use of unistd::getgrouplist.
- Review environments for users with more than 16 /etc/groups memberships.
- Confirm patched nix versions are present after rebuild and redeployment.
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
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CVE-2021-45707 mapping review
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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://rustsec.org/advisories/RUSTSEC-2021-0119.htmlCVE reference · x_refsource_MISC
- https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/nix/RUSTSEC-2021-0119.mdCVE reference · x_refsource_MISC
- https://github.com/advisories/GHSA-wgrg-5h56-jg27CVE 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.