CVE-2025-38331 net: ethernet: cortina: Use TOE/TSO on all TCP
A flaw in the Cortina Ethernet driver causes system lockups and crashes when handling non-segmented TCP frames, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38331?
CVE-2025-38331 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 10 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: cortina: Use TOE/TSO on all TCP
It is desireable to push the hardware accelerator to also process non-segmented TCP frames: we pass the skb->len to the "TOE/TSO" offloader and it will handle them.
Without this quirk the driver becomes unstable and lock up and and crash.
I do not know exactly why, but it is probably due to the TOE (TCP offload engine) feature that is coupled with the segmentation feature - it is not possible to turn one part off and not the other, either both TOE and TSO are active, or neither of them.
Not having the TOE part active seems detrimental, as if that hardware feature is not really supposed to be turned off.
The datasheet says:
"Based on packet parsing and TCP connection/NAT table lookup results, the NetEngine puts the packets belonging to the same TCP connection to the same queue for the software to process. The NetEngine puts incoming packets to the buffer or series of buffers for a jumbo packet. With this hardware acceleration, IP/TCP header parsing, checksum validation and connection lookup are offloaded from the software processing."
After numerous tests with the hardware locking up after something between minutes and hours depending on load using iperf3 I have concluded this is necessary to stabilize the hardware.
Which versions are affected by CVE-2025-38331?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38331?
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-2025-38331 being exploited?
There is no known exploitation of CVE-2025-38331 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64901, AZL-72835, BELL-CVE-2025-38331, DEBIAN-CVE-2025-38331, GHSA-78v2-9wxw-73qf, ROOT-OS-DEBIAN-11-CVE-2025-38331 and 4 more.