CVE-2026-72385 tracing/fprobe: Fix NULL pointer dereference in fprobe_fgraph_entry()
A race condition in the Linux kernel fprobe tracing subsystem can cause a NULL pointer dereference, leading to a system crash.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72385?
CVE-2026-72385 is a vulnerability in Linux, published on 15 Aug 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:
tracing/fprobe: Fix NULL pointer dereference in fprobe_fgraph_entry()
fprobe_fgraph_entry() sizes a shadow-stack reservation in one walk of the per-ip fprobe list and fills it in a second walk, both under rcu_read_lock() only. A fprobe registered on an already-live ip can become visible between the two walks, so the fill walk processes an exit_handler the sizing walk did not count and used runs past reserved_words. If the sizing walk counted nothing, fgraph_data is NULL and the first write_fprobe_header() faults:
Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:fprobe_fgraph_entry+0xa38/0xf10 kernel/trace/fprobe.c:167 Call Trace: <TASK> function_graph_enter_regs+0x44c/0xa10 kernel/trace/fgraph.c:677 ftrace_graph_func+0xc5/0x140 arch/x86/kernel/ftrace.c:671 __kernel_text_address+0x9/0x40 kernel/extable.c:78 arch_stack_walk+0x117/0x170 arch/x86/kernel/stacktrace.c:26 kmem_cache_free+0x188/0x580 mm/slub.c:6378 tcp_data_queue+0x18d/0x6550 net/ipv4/tcp_input.c:5590 [...] </TASK>
The list cannot be frozen across the two walks, so skip a node that does not fit the reservation and count it as missed.
Which versions are affected by CVE-2026-72385?
How do I fix CVE-2026-72385?
Apply the vendor's patch.
Is CVE-2026-72385 being exploited?
There is no known exploitation of CVE-2026-72385 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72385, DEBIAN-CVE-2026-72385, GHSA-hgxp-46qh-fxfr, UBUNTU-CVE-2026-72385.