CVE-2026-43216 net: Drop the lock in skb_may_tx_timestamp()
A null pointer dereference in the Linux kernel network stack can cause a deadlock and system crash when processing TX timestamps in interrupt context.
- 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-2026-43216?
CVE-2026-43216 is a medium-severity vulnerability in Linux kernel, published on 6 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: Drop the lock in skb_may_tx_timestamp()
skb_may_tx_timestamp() may acquire sock::sk_callback_lock. The lock must not be taken in IRQ context, only softirq is okay. A few drivers receive the timestamp via a dedicated interrupt and complete the TX timestamp from that handler. This will lead to a deadlock if the lock is already write-locked on the same CPU.
Taking the lock can be avoided. The socket (pointed by the skb) will remain valid until the skb is released. The ->sk_socket and ->file member will be set to NULL once the user closes the socket which may happen before the timestamp arrives. If we happen to observe the pointer while the socket is closing but before the pointer is set to NULL then we may use it because both pointer (and the file's cred member) are RCU freed.
Drop the lock. Use READ_ONCE() to obtain the individual pointer. Add a matching WRITE_ONCE() where the pointer are cleared.
Weakness: CWE-476
Which versions are affected by CVE-2026-43216?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43216?
Apply the vendor's patch.
Is CVE-2026-43216 being exploited?
There is no known exploitation of CVE-2026-43216 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-85911, BELL-CVE-2026-43216, DEBIAN-CVE-2026-43216, GHSA-r977-p9g8-m7hx, ROOT-OS-DEBIAN-11-CVE-2026-43216, ROOT-OS-DEBIAN-12-CVE-2026-43216 and 4 more.