CVE-2026-65421 MZ Automation libiec61850 Out-of-bounds Read
An attacker can cause a denial of service in the MMS service process by sending malformed BER fields that trigger an out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-65421?
CVE-2026-65421 is a high-severity denial of service 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 BER decoder contains a flaw in decoding fixed-width BER fields (boolean/integer): an attacker-supplied length value is not validated, causing a read past the end of a heap buffer. This leads to termination of the MMS service process and a denial-of-service condition.
Weakness: CWE-125
Which versions are affected by CVE-2026-65421?
How do I fix CVE-2026-65421?
No fix has been published for CVE-2026-65421 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-65421 being exploited?
There is no known exploitation of CVE-2026-65421 in the wild and no public exploit code.
Sources
Also known as GHSA-rh3w-qc85-vjvv.