Exploited. On CISA's list since 2024-05-20, and used by ransomware.

NextGen Healthcare Mirth Connect Deserialization of Untrusted Data Vulnerability

CVE-2023-43208 · NextGen Healthcare Mirth Connect · Published 2023-10-26

How bad would it be?

9.8 out of 10

CVSS rates it critical: about as damaging as flaws get.

How likely is it to be used?

85%

Estimated chance of exploitation in the next 30 days, among the top 1% of all scored flaws (EPSS, 2026-10-29).

Is it already being used?

Yes

CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 872 days ago (2024-06-10).

What CISA says to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

NextGen Healthcare Mirth Connect contains a deserialization of untrusted data vulnerability that allows for unauthenticated remote code execution via a specially crafted request.

nvd.nist.gov

What the flaw 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.

From the NVD.

Learn this

Explore this week’s weaknesses and all learning topics

Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.

OS command injection

Input changes a command that the server runs through its operating system.

CWE-78 · NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov

Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.

Explore the labs at PortSwigger Web Security Academy How it is prevented

Insecure deserialization

Rebuilding objects from untrusted saved data can trigger unintended behaviour.

CWE-502 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.

Explore the labs at PortSwigger Web Security Academy How it is prevented

CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.

On SentryFeed

No story in the last 14 days has mentioned it.

Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.