What is the CVSS score of CVE-2026-91998?

CVE-2026-91998 has a CVSS 4.0 base score of 9.4 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H. EPSS exploitation probability: 0.4%.

Is there a public PoC exploit available for CVE-2026-91998?

Yes, a public proof-of-concept exploit is available for CVE-2026-91998. Prioritise patching immediately. EPSS: 0.4%.

Casdoor CVE-2026-91998

EUVD-2026-78438 CRITICAL

Incorrect Authorization (CWE-863)

2026-09-15 VulnCheck

GHSA-jvmw-g7rg-x26f

Authentication Bypass Casdoor

9.4

CVSS 4.0 · Vendor: VulnCheck

View

Vulnerability Assessment

Weakness

CWE

CWE-863

OWASP Top 10:2025

A01:2025 - Broken Access Control

ASVS 5.0

V8 - Authorization Authorization logic validation

MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

1 PoC candidate (unverified) No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 15, 2026

Cross-organization user administration takeover in Casdoor through 4.4.0 allows any holder of a single application's clientId and clientSecret to act on user accounts across all organizations. The flaw is an authorization bypass in the /api/mcp endpoint that exposes password salts, email addresses, and account creation/modification/deletion capabilities. Public exploit documentation exists, but no active exploitation status or EPSS data was provided.

Affected VersionsENISA

casdoor 0 ≤4.4.0

Affected Packages

euvd casdoor no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (VulnCheck) PRIMARY 9.4 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (VulnCheck) · only source for this CVE.

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

Low

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

High

Vulnerable system: Availability

High

Subsequent system: Confidentiality

High

Subsequent system: Integrity

High

Subsequent system: Availability

High

DescriptionCVE.org

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.

Technical POC Analysis

The flaw is an incorrect authorization decision in Casdoor’s application-credential path, plus unscoped MCP user handlers.

Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.

Latest POC

1 PoC candidate from github (unverified)

Threat Intelligence Overview

EPSS Score

0.4%

Top 65% exploitable

Data Quality

6 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 0.4%

Patch available No

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +47

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

More in Casdoor

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CVE-2026-90942 CRITICAL Act Now POC

9.3 Sep 14

Casdoor through 4.4.0 exposes its instance-wide built-in JWT signing private key unmasked through the /api/get-certs and

CVE-2022-38638 CRITICAL Act Now POC

9.1 Sep 09

Casdoor v1.97.3 was discovered to contain an arbitrary file write vulnerability via the fullFilePath parameter at /api/u

CVE-2024-41657 HIGH This Week POC

8.8 Aug 20

Casdoor is a UI-first Identity and Access Management (IAM) / Single-Sign-On (SSO) platform. Rated high severity (CVSS 8.

CVE-2022-44942 HIGH This Week POC

8.1 Dec 07

Casdoor before v1.126.1 was discovered to contain an arbitrary file deletion vulnerability via the uploadFile function.

CVE-2023-34927 MEDIUM This Month POC

6.5 Jun 22

Casdoor v1.331.0 and below was discovered to contain a Cross-Site Request Forgery (CSRF) in the endpoint /api/set-passwo

CVE-2024-41658 MEDIUM This Month POC

6.1 Aug 20

Casdoor is a UI-first Identity and Access Management (IAM) / Single-Sign-On (SSO) platform. Rated medium severity (CVSS

CVE-2026-15630 CRITICAL Act Now

9.9 Jul 23

Cross-tenant privilege escalation in Casdoor allows a non-global organization admin in one tenant to delete, create, or

CVE-2026-6815 MEDIUM This Month POC

5.9 May 11

Path traversal in Casdoor's Local File System storage provider allows authenticated administrators to write arbitrary fi

CVE-2026-9097 CRITICAL Act Now

9.8 May 28

Token revocation bypass in Casdoor identity management platform (versions 2.362.0 and earlier) allows remote unauthentic

CVE-2026-9094 CRITICAL Act Now

9.8 May 28

Cross-organization token exchange in Casdoor versions 2.362.0 and earlier allows remote unauthenticated attackers to esc

CVE-2026-9093 CRITICAL Act Now

9.8 May 28

SAML authentication bypass in Casdoor 2.362.0 and earlier allows remote unauthenticated attackers to authenticate as arb

CVE-2026-84423 MEDIUM This Month POC

5.5 Sep 01

Unauthenticated arbitrary file upload in Casdoor's /api/upload-resource endpoint (controllers/resource.go) exposes all v

Same weakness CWE-863 – Incorrect Authorization

View all

CVE-2025-54253 CRITICAL POC

10.0

CVE-2025-24200 MEDIUM

6.1

CVE-2026-71362 CRITICAL POC

9.1

CVE-2026-42016 HIGH POC

8.8

CVE-2023-21715 HIGH

7.3

CVE-2025-21480 HIGH

8.6

CVE-2025-21479 HIGH

8.6

CVE-2025-32462 HIGH POC

8.8

Same technique Authentication Bypass

View all

CVE-2015-3306 CRITICAL POC

10.0

CVE-2023-22515 CRITICAL POC

9.8

CVE-2012-4681 CRITICAL POC

9.8

CVE-2013-2465 CRITICAL POC

9.8

CVE-2011-3544 CRITICAL POC

9.8

CVE-2022-40684 CRITICAL POC

9.8

CVE-2025-61882 CRITICAL POC

9.8

CVE-2024-0012 CRITICAL POC

9.3

References

Advisories & patches

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-91998 ADVISORY https://vuldb.com/vuln/404148 REF https://github.com/casdoor/casdoor REF https://github.com/casdoor/casdoor/blob/v4.4.0/authz/authz.go#L174-L176 REF https://github.com/casdoor/casdoor/blob/v4.4.0/mcpself/user.go REF https://github.com/casdoor/casdoor/blob/v4.4.0/routers/base.go#L122-L154 REF https://www.vulncheck.com/advisories/casdoor-through-4.4.0-cross-organization-user-administration-via-api-mcp

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