CVE-2021-4461Known exploitationPublic exploitNetwork attack vector

Unauthenticated impersonation via decoded session attributes

Published Oct 30, 2025 · Updated Oct 30, 2025

Authentication bypass in Seeyon Zhiyuan OA Web Application System 7.0 SP1 and earlier allows remote attackers to impersonate arbitrary users. The thirdpartyController.do handler decodes the enc parameter into map values that influence session attributes without adequate identity checks. No credentials or user interaction are required; a successful request creates an authenticated session for an attacker-selected user ID.

CVSS severity9.3
Critical
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Seeyon Zhiyuan OA Web Application System 7.0 SP1 and earlier allows remote attackers to impersonate arbitrary users. The thirdpartyController.do handler decodes the enc parameter into map values that influence session attributes without adequate identity checks. No credentials or user interaction are required; a successful request creates an authenticated session for an attacker-selected user ID.

The record

CVE
CVE-2021-4461
Published
Oct 30, 2025
Updated
Oct 30, 2025
Vendor
Beijing Seeyon Internet Software Corp.
Product
Zhiyuan OA Web Application System
Classifications
CWE-306, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 30, 2025Exploitation reportedVulnCheck reported in-the-wild exploitation
  2. Oct 30, 2025CVE publishedPublication date reported by the CVE source.
  3. Oct 30, 2025Record 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=0 <=7.0 SP1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Beijing Seeyon Internet Software Corp. · Zhiyuan OA Web Application Systemversion=0 <=7.0 SP1

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA: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.

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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 exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1078Valid Accounts

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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