CVE-2025-39855 ice: fix NULL access of tx->in_use in ice_ptp_ts_irq
A race condition in the Intel E810 network driver causes a kernel NULL pointer dereference, leading to system crashes.
- 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-2025-39855?
CVE-2025-39855 is a high-severity vulnerability in Linux kernel, published on 19 Sep 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:
ice: fix NULL access of tx->in_use in ice_ptp_ts_irq
The E810 device has support for a "low latency" firmware interface to access and read the Tx timestamps. This interface does not use the standard Tx timestamp logic, due to the latency overhead of proxying sideband command requests over the firmware AdminQ.
The logic still makes use of the Tx timestamp tracking structure, ice_ptp_tx, as it uses the same "ready" bitmap to track which Tx timestamps complete.
Unfortunately, the ice_ptp_ts_irq() function does not check if the tracker is initialized before its first access. This results in NULL dereference or use-after-free bugs similar to the following:
[245977.278756] BUG: kernel NULL pointer dereference, address: 0000000000000000 [245977.278774] RIP: 0010:_find_first_bit+0x19/0x40 [245977.278796] Call Trace: [245977.278809] ? ice_misc_intr+0x364/0x380 [ice]
This can occur if a Tx timestamp interrupt races with the driver reset logic.
Fix this by only checking the in_use bitmap (and other fields) if the tracker is marked as initialized. The reset flow will clear the init field under lock before it tears the tracker down, thus preventing any use-after-free or NULL access.
Weakness: CWE-416
Which versions are affected by CVE-2025-39855?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39855?
Apply the vendor's patch.
Is CVE-2025-39855 being exploited?
There is no known exploitation of CVE-2025-39855 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39855, DEBIAN-CVE-2025-39855, GHSA-hvpw-9ghq-558j, UBUNTU-CVE-2025-39855.