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CVE-2026-126473 OpenEMR before 8.4.0 OAuth Authorization Bypass via Scope Canonicalization

9.3 criticalEPSS 0.5%

Critical (9.3) in openemr openemr. EPSS 0.5% estimated probability of exploitation activity in the next 30 days.

On this page
OpenEMR before 8.4.0 contains OAuth scope canonicalization and containment flaws that allow unauthenticated attackers to obtain unapproved system-level FHIR access. Attackers can register a colon-form system:Patient.read client that bypasses approval, then request unregistered system/Patient.write scope to read, modify, and create Patient records.

Severity

CVSS 4.0

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

CVSS 3.1

9.1 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
0.5% estimated probability of exploitation activity in the next 30 days; 40th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CISA's assessment (SSVC)
Exploitation: PoC · Automatable: yes · Technical impact: total, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
CWE
CWE-863 Incorrect Authorization
OWASP Top 10
A01:2025 Broken Access Control
Published
Modified
Assigned by
VulnCheck (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
openemrbefore 8.4.0

References

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