CVE-2026-45873 netfilter: nft_set_rbtree: check for partial overlaps in anonymous sets
A logic error in Linux kernel netfilter allows overlapping intervals in anonymous sets, potentially causing 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-2026-45873?
CVE-2026-45873 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 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:
netfilter: nft_set_rbtree: check for partial overlaps in anonymous sets
Userspace provides an optimized representation in case intervals are adjacent, where the end element is omitted.
The existing partial overlap detection logic skips anonymous set checks on start elements for this reason.
However, it is possible to add intervals that overlap to this anonymous where two start elements with the same, eg. A-B, A-C where C < B.
start end A B start end A C
Restore the check on overlapping start elements to report an overlap.
Which versions are affected by CVE-2026-45873?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45873?
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-2026-45873 being exploited?
There is no known exploitation of CVE-2026-45873 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45873, DEBIAN-CVE-2026-45873, GHSA-9868-rgmf-pm96, ROOT-OS-UBUNTU-2204-CVE-2026-45873, ROOT-OS-UBUNTU-2404-CVE-2026-45873, UBUNTU-CVE-2026-45873.