Security readout for executives and security teams
Plain-English summary
CVE-2020-36456 is a Rust dependency safety issue in the toolshed crate. A type named CopyCell<T> could be marked safe to send between threads without ensuring the contained value was actually safe to send. Business urgency depends on whether your software uses this crate in multithreaded code.
Executive priority
Handle as targeted dependency remediation, not a broad emergency based on current evidence. Raise priority if toolshed is present in production Rust services that use concurrency or process sensitive data.
Technical view
The reported flaw is an unsound Send implementation for CopyCell<T> in toolshed through 2020-11-15. Missing bounds on T may allow non-Send types to cross thread boundaries, undermining Rust's safety guarantees and potentially enabling undefined behavior in affected application code.
Likely exposure
Exposure is limited to Rust applications or libraries that depend on toolshed versions covered by the advisory. Risk is most relevant where CopyCell<T> is used with non-Send inner types or where the affected crate is used in concurrent execution paths.
Exploitation context
The provided sources do not show active exploitation, CVSS scoring, KEV listing, or a public weaponized exploit. This appears to be a dependency-level Rust soundness issue whose impact depends heavily on application usage.
Researcher notes
Evidence is specific but incomplete: the flaw is clearly described as a Send-bound omission, but sources do not provide CVSS, CWE, exploit status, or a named patched version in the supplied bundle. Validate impact through dependency graph and code-path analysis.
Mitigation direction
- Inventory Rust projects for the toolshed crate dependency.
- Check RustSec and upstream crate guidance for fixed or recommended versions.
- Remove or replace toolshed where no maintained fix is available.
- Avoid CopyCell<T> use across threads with non-Send contained types.
- Prioritize review in security-sensitive or multithreaded Rust services.
Validation and detection
- Inspect Cargo.lock for toolshed entries and resolved versions.
- Review code for direct or transitive CopyCell<T> usage.
- Check whether affected code crosses thread boundaries.
- Run dependency auditing against the RustSec advisory database.
- Document whether the application can reach the affected pattern.
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-2020-36456 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-2020-0136.htmlCVE reference · x_refsource_MISC
- https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/toolshed/RUSTSEC-2020-0136.mdCVE 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.