What’s Vulnerable › Vulnerabilities

CVE-2018-12556

• Severity: medium (CVSS 5.9 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-05-16 · updated 2026-06-17
• Weakness: CWE-347

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.

Affected products

• yarnpkg Website: through 2018-06-05

References

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

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