Auth bypass in Casdoor
CVE-2026-91998
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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (48.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.3% 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
Weakness classification (CWE)
References
- github.com/geo-chen/oss/blob/main/casdoor.md (exploit, third-party-advisory)
- github.com/casdoor/casdoor/blob/v4.4.0/authz/authz.go (technical-description)
- github.com/casdoor/casdoor/blob/v4.4.0/routers/base.go (technical-description)
- github.com/casdoor/casdoor/blob/v4.4.0/mcpself/user.go (technical-description)
- github.com/casdoor/casdoor (product)
- www.vulncheck.com/advisories/casdoor-through-4.4.0-cross-organization-user-admi… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-91998?
- CVE-2026-91998 is a critical-severity vulnerability in Casdoor, classified under Incorrect Authorization. CVSS score: 9.9/10. Published 2026-09-15.
- How severe is CVE-2026-91998?
- Critical severity. CVSS v3 base score is 9.9 out of 10.