CVE-2026-91998
CVE-2026-91998 is a critical-severity vulnerability with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.
Key facts
- Severity: Critical (CVSS 3.x base score 9.9)
- CVSS v4: 9.4
- EPSS exploit prediction: 1% (48th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-863
- Published:
- Last modified:
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.
Frequently asked questions
- What is 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.
- How severe is CVE-2026-91998?
- CVE-2026-91998 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-91998 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-91998?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-91998 published?
- CVE-2026-91998 was published on 2026-09-15 and last updated on 2026-09-23.
References
- https://github.com/casdoor/casdoor
- https://github.com/casdoor/casdoor/blob/v4.4.0/authz/authz.go#L174-L176
- https://github.com/casdoor/casdoor/blob/v4.4.0/mcpself/user.go
- https://github.com/casdoor/casdoor/blob/v4.4.0/routers/base.go#L122-L154
- https://github.com/geo-chen/oss/blob/main/casdoor.md#finding-2-application-credential-authorization-bypass-in-apimcp-enables-unrestricted-cross-organization-user-administration
- https://www.vulncheck.com/advisories/casdoor-through-4.4.0-cross-organization-user-administration-via-api-mcp
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