Security readout for executives and security teams
Plain-English summary
CVE-2021-29939 is a memory-safety issue in the Rust stackvector crate. Under unusual size_hint data, StackVec::extend can write outside its intended bounds. Business urgency depends on whether your software uses this crate and whether attacker-controlled iterator data can reach that code.
Executive priority
Treat as an inventory-driven remediation item, not an emergency unless stackvector is present in exposed Rust services with untrusted input paths.
Technical view
The source bundle describes an out-of-bounds write in StackVec::extend in stackvector through 2021-02-19, triggered by anomalous size_hint values. No CVSS, CWE, affected CPEs, fixed version, or exploit details are provided in the supplied sources.
Likely exposure
Exposure is likely limited to Rust applications or libraries that depend on stackvector versions covered by the advisory and call StackVec::extend on data influenced by untrusted inputs.
Exploitation context
The bundle does not cite active exploitation, and KEV is false. The issue is memory corruption, but exploitability and real-world reachability are not established by the provided sources.
Researcher notes
Evidence is sparse: the record names the vulnerable function and condition, but not fixed versions, CVSS scoring, CWE mapping, or known exploitation. Avoid assuming impact beyond an out-of-bounds write without local reachability analysis.
Mitigation direction
- Inventory Rust projects for the stackvector crate dependency.
- Review the RustSec advisory and maintainer guidance for fixed or safe versions.
- Remove or replace stackvector if no trustworthy remediation is available.
- Prioritize services where untrusted data reaches StackVec::extend.
Validation and detection
- Check Cargo.toml and lockfiles for stackvector dependency paths.
- Use RustSec-aware dependency auditing to flag vulnerable stackvector versions.
- Review code paths for StackVec::extend usage with untrusted iterators.
- Confirm remediation by verifying stackvector is removed or updated per advisory guidance.
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-2021-29939 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://rustsec.org/advisories/RUSTSEC-2021-0048.htmlCVE 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.