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CVE-2021-27884

18
FAUCET Score

CVE-2021-27884 describes a weakness in YMFE YApi through version 1.9.2, where JSON Web Token (JWT) signing secrets are generated using Node.js's Math.random, making them predictable and allowing attackers to recreate other users' tokens. This vulnerability has a CVSS score of 5.1 (MEDIUM), indicating a local attack vector with low complexity, potentially leading to limited confidentiality and integrity impact. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.9.2CPE matchmatch criteria
cpe:2.3:a:ymfe:yapi:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.1MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.5
Impact Score
2.5
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.34%
Probability of exploitation in next 30 days
EPSS Percentile
26.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0034 is in the 38th percentile among its peer group of 3,052 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

npmpatch availablevia ghsa
Product: yapi-vendorFixed in: 1.9.3

Vendor Advisories (1)

npmGHSA-2h3h-vw8r-82rpmedium

Weak JSON Web Token in yapi-vendor

Mar 26, 2021

References

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