Security readout for executives and security teams
Plain-English summary
CVE-2021-38195 affects the Rust libsecp256k1 crate before version 0.5.0. The library could accept an invalid cryptographic signature when signature values exceed the curve order. Business risk depends on whether the crate is used to make trust, authorization, transaction, or integrity decisions.
Executive priority
Treat as targeted dependency remediation. Escalate if the affected crate protects financial, authentication, blockchain, or integrity workflows; otherwise handle through normal dependency update cycles.
Technical view
The issue is an overflow-related ECDSA verification flaw in libsecp256k1 before 0.5.0. The verifier allowed R or S parameters larger than the secp256k1 curve order, which could cause invalid signatures to verify as valid.
Likely exposure
Exposure is limited to Rust applications or libraries that directly or transitively depend on libsecp256k1 versions before 0.5.0. Impact is highest where signature verification gates security-sensitive decisions.
Exploitation context
The supplied sources do not report active exploitation, and the CVE is not marked KEV. They only state that invalid signatures can verify under the affected condition.
Researcher notes
Evidence is narrow but clear: RustSec and CVE sources identify the vulnerable crate, affected versions, and verification failure mode. No CVSS, CWE, exploit maturity, or downstream product list is provided.
Mitigation direction
- Upgrade libsecp256k1 to version 0.5.0 or later.
- Regenerate and review Cargo.lock after dependency updates.
- Check transitive dependencies for pinned vulnerable versions.
- Review vendor or RustSec guidance if immediate upgrade is blocked.
- Prioritize systems where signatures authorize funds, identity, or data integrity.
Validation and detection
- Inspect Cargo.toml and Cargo.lock for libsecp256k1 before 0.5.0.
- Check dependency scanner results against RUSTSEC-2021-0076.
- Confirm builds resolve libsecp256k1 to 0.5.0 or later.
- Add regression tests rejecting signatures with out-of-range R or S values.
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-2021-38195 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-2021-0076.htmlCVE reference · x_refsource_MISC
- https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/libsecp256k1/RUSTSEC-2021-0076.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.