CVE-2021-4461

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.

The following products are affected by CVE-2021-4461 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2021-4461.

URL	Resource
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