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CVE-2026-126436 OpenEMR before 8.5.0 OAuth2 Grant Type Enforcement Bypass via Token Endpoint

8.7 highEPSS 0.4%

High (8.7) in openemr openemr. EPSS 0.4% estimated probability of exploitation activity in the next 30 days.

On this page
OpenEMR before 8.5.0 contains an authorization bypass vulnerability that allows OAuth2 clients to use unregistered grant types because oauth_clients.grant_types is never enforced. Attackers can request tokens with grant_type=password to bypass the user consent screen, and disabled clients can redeem authorization codes using JWT client assertions.

Severity

CVSS 4.0

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

CVSS 3.1

7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
0.4% estimated probability of exploitation activity in the next 30 days; 38th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CISA's assessment (SSVC)
Exploitation: none · Automatable: yes · Technical impact: partial, 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-862 Missing Authorization
OWASP Top 10
A01:2025 Broken Access Control
Published
Modified
Assigned by
VulnCheck (CNA)
NVD analysis
Under analysis
Record from
the NVD, synced

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
openemrbefore 8.5.0

Attack patterns (CAPEC)

  • CAPEC-665 Exploitation of Thunderbolt Protection Flaws Likelihood: Low · Severity: Very High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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