CVE
OpenEMR authorization bypass in OAuth2 token endpoint
Affects OpenEMR before 8.5.0 when the password grant is enabled or a confidential client uses a JWKS with JWT client assertion. Fixed in 8.5.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 8.5.0
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. The password grant is enabled (oauth_password_grant global). For the disabled-client path, the client is registered with a JWKS and uses JWT client assertion authentication.
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.43% · 38th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 21/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
Who should check
Teams running OpenEMR before 8.5.0 with the password grant enabled, or with OAuth2 clients that use JWT client assertions, such as patient-facing SMART app integrations.
Read the source excerpt
“OpenEMR before 8.5.0 contains an authorization bypass vulnerability”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
The password grant is enabled (oauth_password_grant global). For the disabled-client path, the client is registered with a JWKS and uses JWT client assertion authentication.Upgrade to a fixed version: 8.5.0.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126436 (OpenEMR before 8.5.0 OAuth2 Grant Type Enforcement Bypass via Token Endpoint), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126436 (entry last updated 2026-11-13):
Affected:
- openemr openemr: fixed in 8.5.0
Fixed versions: 8.5.0.
Conditions (all must be true for the bug to be hit):
- The password grant is enabled (oauth_password_grant global). (source: https://github.com/openemr/openemr/security/advisories/GHSA-qjj7-c4m9-6f92)
- For the disabled-client path, the client is registered with a JWKS and uses JWT client assertion authentication. (source: https://github.com/openemr/openemr/security/advisories/GHSA-qjj7-c4m9-6f92)
Setup: the bug needs a feature or setting that is off by default or uncommon. Check whether each asset has it on.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-126436 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126436 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/openemr/openemr/security/advisories/GHSA-qjj7-c4m9-6f92
- https://www.vulncheck.com/advisories/openemr-before-8.5.0-oauth2-grant-type-enforcement-bypass-via-token-endpoint
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126436
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126436"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- openemr openemr
fixed in 8.5.0
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126436
Is CVE-2026-126436 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The token endpoint issues a token carrying whatever registered scopes the client requests, without user review, so consent is bypassed. A disabled client can also redeem authorization codes that were issued before it was disabled.Source: github.com
Which versions are affected by CVE-2026-126436?
openemr: before 8.5.0.Source: cve.now feed data
Am I affected, and how do I check?
Versions before 8.5.0 are in range. The consent bypass applies when the password grant is enabled (the oauth_password_grant global setting). The disabled-client path applies to a confidential client registered with a JWKS that uses JWT client assertion authentication. Check the OpenEMR version and the oauth_password_grant setting to see which of these apply.Source: github.com
How do I fix CVE-2026-126436?
Upgrade OpenEMR to 8.5.0 or later, which is the fixed version in the affected range.Source: github.com