CVE-2026-74477: uprobes: Fix NULL pointer dereference in hprobe_expire()
In the Linux kernel, the following vulnerability has been resolved:
uprobes: Fix NULL pointer dereference in hprobeexpire()
Forking a task that has a pending uretprobe can oops the kernel with a NULL pointer dereference in the clone() path:
BUG: kernel NULL pointer dereference, address: 0000000000000018 Oops: 0002 [#1] SMP NOPTI RIP: 0010:hprobeexpire CR2: 0000000000000018 Call Trace: uprobecopyprocess copyprocess kernelclone x64sysclone dosyscall64 entrySYSCALL64afterhwframe
This was found on real hosts on Meta fleet.
I've got the impression that this is what is happening:
CPU 1 CPU 2 (traced task) ----- ------------------- hit uprobe, prepareuretprobe(): hprobe LEASED, refcount >= 1 uprobeunregister() putuprobe(): refcount -> 0 fork() -> duputask() hprobeexpire(hprobe, true) trygetuprobe() -> NULL getuprobe(NULL) <-- Oops
Only take the extra reference when the uprobe is non-NULL; a NULL means it is gone and is the correct value to return.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74477?
CVE-2026-74477 has a risk rating of 44.
What causes the CVE-2026-74477 vulnerability?
CVE-2026-74477 is caused by a NULL pointer dereference in the hprobe_expire() function when forking a task with a pending uretprobe.
How do I fix CVE-2026-74477?
To fix CVE-2026-74477, update to the latest version of the Linux Kernel where the vulnerability has been patched.
What systems are affected by CVE-2026-74477?
CVE-2026-74477 affects systems running the vulnerable versions of the Linux Kernel that implement uprobes.
When was CVE-2026-74477 published?
CVE-2026-74477 was published on August 15, 2026.