Vulnerability · Published Sep 15, 2026 · Assigned by VulnCheck

CVE-2026-91998Casdoor through 4.4.0 Cross-Organization User Administration via /api/mcp

Critical 9.9

In plain English

A critical-severity incorrect authorization in casdoor from casdoor. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities).

Severity (CVSS 3.1)9.9Critical

Exploit odds (30 days)0.6%top 51.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

Casdoor through 4.4.0 contains an authorization bypass vulnerability in the /api/mcp endpoint that allows attackers with any application's clientId and clientSecret to gain unrestricted access to user administration across all organizations. Attackers can enumerate user records including password salts and email addresses, create administrator accounts, modify existing users, and delete them in any organization by supplying legitimate credentials from a single application.

Affected products (as reported)

Vendor	Product	Versions
casdoor	casdoor	0 – through 4.4.0

Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

Researcher write-up, Finding 2 third-party-advisory, exploit
authz/authz.go unconditional app allow at v4.4.0 technical-description
getUsernameByClientIdSecret at v4.4.0 technical-description
mcpself/user.go unscoped user tools at v4.4.0 technical-description
https://github.com/casdoor/casdoor product
VulnCheck Advisory: Casdoor through 4.4.0 Cross-Organization User Administration via /api/mcp third-party-advisory