CVE-2021-21403Network attack vector

Unauthenticated account access via inverted code verification

Published Mar 26, 2021 · Updated Aug 3, 2024

Authentication bypass in Kongchuanhujiao ProvinceServer before 1.3.21 allows remote attackers to access user accounts through the login API. The PostLogin handler accepts a nonempty verification code when VerifyCode reports that it does not match the code stored for the supplied user ID. No credentials or user interaction are required, and successful exploitation exposes account-confidential data without reported write or service-interruption impact.

CVSS severity9.8
Critical
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Kongchuanhujiao ProvinceServer before 1.3.21 allows remote attackers to access user accounts through the login API. The PostLogin handler accepts a nonempty verification code when VerifyCode reports that it does not match the code stored for the supplied user ID. No credentials or user interaction are required, and successful exploitation exposes account-confidential data without reported write or service-interruption impact.

The record

CVE
CVE-2021-21403
Published
Mar 26, 2021
Updated
Aug 3, 2024
Vendor
Kongchuanhujiao
Product
ProvinceServer
Classifications
CWE-305, CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.3.21

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kongchuanhujiao · ProvinceServerversion=< 1.3.21

Published CVSS scores

7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-305Authentication Bypass by Primary Weakness
CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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