Auth bypass in Seeyon Zhiyuan Oa Web Application System
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.
Vulnerability class: Broken Authentication
Published · last modified .
EPSS exploit prediction
EPSS: 0.006 (46.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- Seeyon Zhiyuan Oa Web Application System — versions 0
Weakness classification (CWE)
References
- mp.weixin.qq.com/s/0AqdfTrZUVrwTMbKEKresg (exploit)
- github.com/chaitin/xray/blob/f90cf321bc4d294bbf6625a9c4853f3bfdf0a384/pocs/seey… (exploit)
- github.com/projectdiscovery/nuclei-templates/blob/1ca6b8e6fe225cbd46dcb893dcaee… (exploit)
- www.vulncheck.com/advisories/seeyon-zhiyuan-oa-web-application-system-authentic… (third-party-advisory)