CVE-2026-43491 net: qrtr: ns: Limit the maximum server registration per node
A malicious client can exhaust kernel memory by flooding server registration messages in the QRTR network subsystem, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43491?
CVE-2026-43491 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: qrtr: ns: Limit the maximum server registration per node
Current code does no bound checking on the number of servers added per node. A malicious client can flood NEW_SERVER messages and exhaust memory.
Fix this issue by limiting the maximum number of server registrations to 256 per node. If the NEW_SERVER message is received for an old port, then don't restrict it as it will get replaced. While at it, also rate limit the error messages in the failure path of qrtr_ns_worker().
Note that the limit of 256 is chosen based on the current platform requirements. If requirement changes in the future, this limit can be increased.
Which versions are affected by CVE-2026-43491?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43491?
Apply the vendor's patch.
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-2026-43491 being exploited?
There is no known exploitation of CVE-2026-43491 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-86981, BELL-CVE-2026-43491, DEBIAN-CVE-2026-43491, GHSA-vfqf-4c37-r857, ROOT-OS-DEBIAN-11-CVE-2026-43491, ROOT-OS-DEBIAN-12-CVE-2026-43491 and 3 more.