CVE-2026-40507Public exploitNetwork attack vector

Session hijacking via unsanitized templateHtml reflection

Published Aug 19, 2026 · Updated Aug 25, 2026

Reflected XSS in OpenEMR before 8.3.0 allows remote attackers to hijack authenticated Forms Administration sessions via crafted URLs. The templateHtml GET branch in portal/import_template.php passes the parameter directly to renderEditorHtml without sanitization or output encoding. Exploitation requires a Forms Administration user to open the link, after which attacker-supplied JavaScript executes in that user's authenticated browser session.

CVSS severity5.1
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in OpenEMR before 8.3.0 allows remote attackers to hijack authenticated Forms Administration sessions via crafted URLs. The templateHtml GET branch in portal/import_template.php passes the parameter directly to renderEditorHtml without sanitization or output encoding. Exploitation requires a Forms Administration user to open the link, after which attacker-supplied JavaScript executes in that user's authenticated browser session.

The record

CVE
CVE-2026-40507
Published
Aug 19, 2026
Updated
Aug 25, 2026
Vendor
OpenEMR Foundation
Product
OpenEMR
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <8.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenEMR Foundation · OpenEMRversion=0 <8.3.0

Published CVSS scores

5.1VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
6.1VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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