CVE-2023-43208 NextGen Healthcare Mirth Connect Deserialization of Untrusted Data Vulnerability
NextGen Healthcare Mirth Connect contains a deserialization of untrusted data vulnerability that allows for unauthenticated remote code execution via a specially crafted request.
From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.
Should You Worry?
- CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 20 May 2024.
- CISA lists it as known to be used in ransomware campaigns.
- Rated Critical severity (CVSS 9.8, scored by CISA).
- It has been in the catalogue for 900 days. Systems still unpatched now have almost certainly been scanned for it.
What It Is
NextGen Healthcare Mirth Connect before version 4.4.1 is vulnerable to unauthenticated remote code execution. Note that this vulnerability is caused by the incomplete patch of CVE-2023-37679.
What To Do Now
- 1
Find it
Search your asset inventory and external attack surface for NextGen Healthcare Mirth Connect. Include cloud images, appliances and anything a supplier runs for you.
Attack Surface Management - 2
Fix it
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vulnerability Management - 3
Hunt for compromise
If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.
Incident Response - 4
Prove it is fixed
Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.
Penetration Testing
Vendor Advisories
The Compliance Clock
General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.
More Exploited NextGen Healthcare Flaws
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