What is CVE-2021-21403?

CVE-2021-21403 is a high-severity vulnerability in Kongchuanhujiao Server, classified under Authentication Bypass by Primary Weakness. CVSS score: 7.5/10. Published 2021-03-26.

How severe is CVE-2021-21403?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-21403 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Auth bypass in Kongchuanhujiao Server

CVE-2021-21403

In github.com/kongchuanhujiao/server before version 1.3.21 there is an authentication Bypass by Primary Weakness vulnerability. All users are impacted. This is fixed in version 1.3.21.

Published 2021-03-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.014 (70.8th percentile), scored 2026-10-07.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Kongchuanhujiao Server — versions < 1.3.21
Kongchuanhujiao Project

Weakness classification (CWE)

Public proof-of-concept exploits

5l1v3r1/CVE-2021-21403

References

github.com/kongchuanhujiao/server/security/advisories/GHSA-8wrg-m8vm-5fvj (Third Party Advisory)
github.com/kongchuanhujiao/server/commit/9a125624f219e496bdf4b07b404816d5a309bd… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-21403?: CVE-2021-21403 is a high-severity vulnerability in Kongchuanhujiao Server, classified under Authentication Bypass by Primary Weakness. CVSS score: 7.5/10. Published 2021-03-26.
How severe is CVE-2021-21403?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-21403 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.