What’s Vulnerable › Vulnerabilities

CVE-2021-4461: Seeyon Zhiyuan OA Web Application System < 7.0 SP1 Authentication Bypass

• Severity: critical (CVSS 9.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-30 · updated 2026-06-17
• Weakness: CWE-306

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.

Affected products

• Seeyon Zhiyuan OA Web Application System: through 7.0 SP1

References

• https://github.com/chaitin/xray/blob/f90cf321bc4d294bbf6625a9c4853f3bfdf0a384/pocs/seeyon-oa-cookie-leak.yml
• https://github.com/projectdiscovery/nuclei-templates/blob/1ca6b8e6fe225cbd46dcb893dcaee01447afa8c0/http/misconfiguration/seeyon-unauth.yaml#L20
• https://mp.weixin.qq.com/s/0AqdfTrZUVrwTMbKEKresg
• https://www.vulncheck.com/advisories/seeyon-zhiyuan-oa-web-application-system-authentication-bypass

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