Weak JSON Web Token in yapi-vendor

published 2021-03-01 5y ago modified 2026-06-17 4mo ago also GHSA-2h3h-vw8r-82rp , EUVD-2021-0584

cvss: 5.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits: 0; none known

Weak JSON Web Token (JWT) signing secret generation in YMFE YApi through 1.9.2 allows recreation of other users' JWT tokens. This occurs because Math.random in Node.js is used.

Patch / fix

fixed in 1

npm yapi-vendor 1.9.3

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Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD	2.0	3.6	AV:L/AC:L/Au:N/C:P/I:P/A:N
GitHub	3.1	5.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	yapi-vendor	<1.9.3	1.9.3

Classification

Weakness

CWE-330 Use of Insufficiently Random Values

References

securitylab.github.com /advisories/GHSL-2020-228-YMFE-yapi
advisory, third-party-advisory
github.com /YMFE/yapi/issues/2117
web, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2021-27884
advisory
github.com /YMFE/yapi/issues/2263
web

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.