CVE-2025-39973 i40e: add validation for ring_len param
A missing validation in the i40e network driver allows a virtual function to cause a denial of service by providing invalid ring lengths.
- 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-2025-39973?
CVE-2025-39973 is a high-severity denial of service vulnerability in Linux, published on 15 Oct 2025. 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:
i40e: add validation for ring_len param
The `ring_len` parameter provided by the virtual function (VF) is assigned directly to the hardware memory context (HMC) without any validation.
To address this, introduce an upper boundary check for both Tx and Rx queue lengths. The maximum number of descriptors supported by the hardware is 8k-32. Additionally, enforce alignment constraints: Tx rings must be a multiple of 8, and Rx rings must be a multiple of 32.
Which versions are affected by CVE-2025-39973?
How do I fix CVE-2025-39973?
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-2025-39973 being exploited?
There is no known exploitation of CVE-2025-39973 in the wild and no public exploit code.
Sources
Also known as AZL-68495, BELL-CVE-2025-39973, DEBIAN-CVE-2025-39973, GHSA-j9g6-49hr-w92p, ROOT-OS-DEBIAN-11-CVE-2025-39973, ROOT-OS-DEBIAN-12-CVE-2025-39973 and 3 more.