CVE-2026-33592 FindServers Memory Exhaustion in open62541
An unauthenticated remote attacker can exhaust server memory in open62541 by sending large FindServers requests, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33592?
CVE-2026-33592 is a high-severity denial of service vulnerability in open62541, published on 2 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An unauthenticated remote attacker can exhaust server memory via the FindServers Discovery Service in open62541. The serverUris field of FindServersRequest is not validated for length or array size. An attacker can declare an arbitrarily large string (up to ~3.9 GB) delivered across intermediate chunks without ever sending the final chunk. The server buffers all chunks in RAM indefinitely until the SecureChannel times out. The attack is pre-session and bypasses all encryption configuration. The issue affects open62541: from 1.4.0 through 1.4.16, from 1.5.0 through 1.5.4, master.
Which versions are affected by CVE-2026-33592?
How do I fix CVE-2026-33592?
No fix has been published for CVE-2026-33592 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-2026-33592 being exploited?
There is no known exploitation of CVE-2026-33592 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-33592, GHSA-r94m-59fw-hm34, UBUNTU-CVE-2026-33592.