{"id":"CVE-2021-4461","details":"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.","modified":"2026-10-20T10:55:45.417238520Z","published":"2025-10-30T22:15:41.633Z","database_specific":{},"references":[{"type":"WEB","url":"https://github.com/chaitin/xray/blob/f90cf321bc4d294bbf6625a9c4853f3bfdf0a384/pocs/seeyon-oa-cookie-leak.yml"},{"type":"WEB","url":"https://github.com/projectdiscovery/nuclei-templates/blob/1ca6b8e6fe225cbd46dcb893dcaee01447afa8c0/http/misconfiguration/seeyon-unauth.yaml#L20"},{"type":"WEB","url":"https://mp.weixin.qq.com/s/0AqdfTrZUVrwTMbKEKresg"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/seeyon-zhiyuan-oa-web-application-system-authentication-bypass"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/projectdiscovery/nuclei-templates","events":[{"introduced":"0"},{"last_affected":"cb5d5b9f0d0290b4343199defc8837aa7b39bf6e"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"0"},{"last_affected":"7.0"}],"source":"DESCRIPTION"}]}}],"versions":["v7.0.0","v6.0.9","v6.0.8","v6.0.7","v6.0.6","v6.0.5","v6.0.4","v6.0.3","v6.0.2","v6.0.1","v6.0.0","v5.0.9","v5.0.8","v5.0.7","v3.0.5","v5.0.6","v5.0.5","v4.0.0","v5.0.4","v5.0.3","v5.0.2","v5.0.1","v5.0.0","v4.0.9","v4.0.8","v4.0.7","v4.0.6","v4.0.5","v4.0.4","v4.0.3","v4.0.2","v4.0.1","v3.0.9","v3.0.8","v3.0.7","v3.0.6","v3.0.4","v3.0.3","v3.0.2","v3.0.1","v3.0.0","v2.0.9","v2.0.8","v2.0.7","v2.0.6","v2.0.5","v2.0.4","v2.0.3","v2.0.2","v2.0.0","v1.1.9","v1.1.8","v1.1.7","v1.1.6","v1.1.5","v1.1.4","v1.1.3","v1.1.2","v1.1.1","v1.1.0","v1.0.9","v1.0.8","v1.0.7","v1.0.6","v1.0.5","v1.0.4","v1.0.3","v1.0.2","v1.0.1","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-4461.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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:X/V:X/RE:X/U:X"}]}