CVE-2021-4461 CRITICAL

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

Vendor Seeyon
Product Zhiyuan OA Web Application System
Weakness CWE-306 · Missing auth
Published October 30, 2025
Last update November 28, 2025

CVSS base score

9.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

October 30, 2025 CVE published
November 28, 2025 Record updated