CVE-2026-66349 MZ Automation libiec61850 Out-of-bounds Read
An attacker can cause a denial of service in the MMS server by sending a malformed BER-encoded request that triggers an out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-66349?
CVE-2026-66349 is a medium-severity memory corruption vulnerability in MZ Automation GmbH libiec61850, published on 30 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
The MMS server connection handler contains a flaw in its processing of BER-encoded request data. When an MMS confirmed request PDU containing an extended BER tag is received over an established session, the decoder may advance its internal buffer incorrectly due to a missing bounds check. This results in a one byte heap out-of-bounds read and causes the MMS service process to terminate, leading to a denial-of-service condition.
Weakness: CWE-125
Which versions are affected by CVE-2026-66349?
How do I fix CVE-2026-66349?
No fix has been published for CVE-2026-66349 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-66349 being exploited?
There is no known exploitation of CVE-2026-66349 in the wild and no public exploit code.
Sources
Also known as GHSA-8m3p-4g59-6h2r.