What is CVE-2021-27884?

CVE-2021-27884 is a medium-severity vulnerability in Ymfe Yapi, classified under Use of Insufficiently Random Values. CVSS score: 5.1/10. Published 2021-03-01.

How severe is CVE-2021-27884?

Medium severity. CVSS v3 base score is 5.1 out of 10.

Vulnerability in Ymfe Yapi

CVE-2021-27884

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.

Published 2021-03-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.1 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (24.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 24.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Ymfe Yapi

Weakness classification (CWE)

CWE-330 — Use of Insufficiently Random Values

References

securitylab.github.com/advisories/GHSL-2020-228-YMFE-yapi (Third Party Advisory)
github.com/YMFE/yapi/issues/2117 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-27884?: CVE-2021-27884 is a medium-severity vulnerability in Ymfe Yapi, classified under Use of Insufficiently Random Values. CVSS score: 5.1/10. Published 2021-03-01.
How severe is CVE-2021-27884?: Medium severity. CVSS v3 base score is 5.1 out of 10.