CVE-2026-91998

CRITICALPre-NVD 9.99.9—
EchelonGraph scoreHIGH confidence

Score 9.9 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-15. a secondary CVSS source baseline 9.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
9.9EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.9Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.9
EG Score
9.9(high)
EG Risk
61(Track*)
EG Risk 61/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity99% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 17, 2026

Advisory Details (6)

Auto-updated Sep 17, 2026
No patch confirmed yet.
generic

Casdoor through 4.4.0 Cross-Organization User Administration via /api/mcp | Advisories | VulnCheck

https://www.vulncheck.com/advisories/casdoor-through-4.4.0-cross-organization-user-administration-via-api-mcp
generic

oss/casdoor.md at main · geo-chen/oss · GitHub

https://github.com/geo-chen/oss/blob/main/casdoor.md#finding-2-application-credential-authorization-bypass-in-apimcp-enables-unrestricted-cross-organization-user-administration
generic

casdoor/routers/base.go at v4.4.0 · casdoor/casdoor · GitHub

https://github.com/casdoor/casdoor/blob/v4.4.0/routers/base.go#L122-L154
generic

casdoor/mcpself/user.go at v4.4.0 · casdoor/casdoor · GitHub

https://github.com/casdoor/casdoor/blob/v4.4.0/mcpself/user.go
generic

casdoor/authz/authz.go at v4.4.0 · casdoor/casdoor · GitHub

https://github.com/casdoor/casdoor/blob/v4.4.0/authz/authz.go#L174-L176
generic

GitHub - casdoor/casdoor: An open-source Agent-first Identity and Access Management (IAM) /LLM MCP & agent gateway and auth server with web UI supporting OpenClaw, MCP, OAuth, OIDC, SAML, CAS, LDAP, SCIM, WebAuthn, TOTP, MFA, Face ID, Google Workspace, Azure AD · GitHub

https://github.com/casdoor/casdoor

Vendor Advisories for CVE-2026-91998(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 41× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-20 03:10 UTCGHSA enrichment
  2. 2026-09-19 23:17 UTCGHSA enrichment
  3. 2026-09-19 19:25 UTCEG score recompute
  4. 2026-09-19 19:25 UTCGHSA enrichment
  5. 2026-09-19 15:32 UTCGHSA enrichment
  6. 2026-09-19 11:38 UTCGHSA enrichment
  7. 2026-09-19 07:39 UTCGHSA enrichment
  8. 2026-09-19 03:46 UTCGHSA enrichment
  9. 2026-09-18 23:53 UTCGHSA enrichment
  10. 2026-09-18 20:01 UTCEG score recompute
  11. 2026-09-18 20:01 UTCGHSA enrichment
  12. 2026-09-18 19:28 UTCEPSS rescore
  13. 2026-09-18 16:08 UTCGHSA enrichment
  14. 2026-09-18 11:59 UTCGHSA enrichment
  15. 2026-09-18 08:07 UTCGHSA enrichment
  16. 2026-09-18 04:14 UTCGHSA enrichment
  17. 2026-09-18 00:22 UTCGHSA enrichment
  18. 2026-09-17 20:29 UTCEG score recompute
  19. 2026-09-17 20:29 UTCGHSA enrichment
  20. 2026-09-17 19:39 UTCEG score recompute
  21. 2026-09-17 19:39 UTCGHSA enrichment
  22. 2026-09-17 19:32 UTCEPSS rescore
  23. 2026-09-17 19:23 UTCGHSA enrichment
  24. 2026-09-17 13:18 UTCGHSA enrichment
  25. 2026-09-17 09:26 UTCGHSA enrichment
Show 16 more
  1. 2026-09-17 05:33 UTCGHSA enrichment
  2. 2026-09-17 01:40 UTCGHSA enrichment
  3. 2026-09-16 21:47 UTCGHSA enrichment
  4. 2026-09-16 17:55 UTCEG score recompute
  5. 2026-09-16 17:55 UTCGHSA enrichment
  6. 2026-09-16 14:09 UTCEPSS rescore
  7. 2026-09-16 12:40 UTCGHSA enrichment
  8. 2026-09-16 08:48 UTCGHSA enrichment
  9. 2026-09-16 04:03 UTCGHSA enrichment
  10. 2026-09-16 00:08 UTCGHSA enrichment
  11. 2026-09-15 20:15 UTCGHSA enrichment
  12. 2026-09-15 16:22 UTCEG score recompute
  13. 2026-09-15 16:22 UTCGHSA enrichment
  14. 2026-09-15 12:30 UTCEG score recompute
  15. 2026-09-15 11:43 UTCEG score recompute
  16. 2026-09-15 11:42 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-91998?
CVE-2026-91998 is a critical vulnerability published on September 15, 2026. 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…
When was CVE-2026-91998 disclosed?
CVE-2026-91998 was first published in the National Vulnerability Database on September 15, 2026, with the most recent update on September 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91998 actively exploited?
CVE-2026-91998 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 64.3% of all scored CVEs.
What is the CVSS score of CVE-2026-91998?
CVE-2026-91998 has a CVSS v3 base score of 9.9 (NVD).
How do I remediate CVE-2026-91998?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91998, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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