CVE-2026-1301 Out-of-bounds Write in o6 Automation GmbH Open62541
A crafted JSON message in Open62541 with PubSub enabled causes an out-of-bounds write, leading to crashes or potential code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-1301?
CVE-2026-1301 is a medium-severity memory corruption vulnerability in o6 Automation GmbH Open62541, published on 5 Feb 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
In builds with PubSub and JSON enabled, a crafted JSON message can cause the decoder to write beyond a heap-allocated array before authentication, reliably crashing the process and corrupting memory.
Weakness: CWE-787
Which versions are affected by CVE-2026-1301?
How do I fix CVE-2026-1301?
No fix has been published for CVE-2026-1301 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-2026-1301 being exploited?
There is no known exploitation of CVE-2026-1301 in the wild and no public exploit code.
Sources
Also known as GHSA-c8xh-89h3-73pj.