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Vulnerability record · CVE-2021-4461 · published 30 October 2025

CVE-2021-4461: Missing authentication for critical function vulnerability

Seeyon Zhiyuan OA Web Application System versions up to and including 7.0 SP1 improperly decode and parse the `enc` parameter in thirdpartyController.do. The decoded map values can influence session attributes without sufficient authentication/authorization checks, enabling attackers to assign a session to arbitrary user IDs. VulnCheck has observed this vulnerability being exploited in the wild as of 2025-10-30 at 00:30:40.855917 UTC.

9.3 CVSS 4.0 Critical EPSS 0.60% · top 53.7% CWE-306 · Missing authentication for critical function Deferred
9.3CVSS 4.0 base score
0.60%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Seeyon Zhiyuan OA Web Application System versions up to and including 7.0 SP1 improperly decode and parse the `enc` parameter in thirdpartyController.do. The decoded map values can influence session attributes without sufficient authentication/authorization checks, enabling attackers to assign a session to arbitrary user IDs. VulnCheck has observed this vulnerability being exploited in the wild as of 2025-10-30 at 00:30:40.855917 UTC.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/chaitin/xray/blob/f90cf321bc4d294bbf6625a9c4853f3bfdf0a384/pocs/seeyon-oa-cookie-leak.yml
https://github.com/projectdiscovery/nuclei-templates/blob/1ca6b8e6fe225cbd46dcb893dcaee01447afa8c0/http/misconfiguration
https://mp.weixin.qq.com/s/0AqdfTrZUVrwTMbKEKresg
https://www.vulncheck.com/advisories/seeyon-zhiyuan-oa-web-application-system-authentication-bypass

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Source: NIST National Vulnerability Database (record CVE-2021-4461), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.