Live › vulnerability › CVE-2026-99173
Go to dashboardIn the Linux kernel's tracefs/eventfs code, a path lookup running under RCU can read an eventfs_inode that was already freed when its dentry is torn down. The sources describe a KASAN slab-use-after-free, which can crash the kernel or let a local user read freed memory.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-28 11:32 UTC. All times on this page are UTC.
Systems running a Linux kernel with eventfs and tracefs in use, typically hosts where ftrace or tracing is mounted. The sources do not say whether unprivileged users can trigger it, and tracefs is usually only mounted on machines that use kernel tracing. Machines without tracefs mounted are unlikely to be exposed.
No product ranges from the sources yet.
uname -r and compare the running kernel against the fixed kernel versions in the stable tree (unknown: the sources do not list them)mount | grep tracefs (unknown: the sources do not say this is the only trigger)Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
eventfs: Free the eventfs_inode after an rcu grace period too
tracefs_d_revalidate() reads ->is_freed of the eventfs_inode that dentry->d_fsdata points to, and ->d_revalidate() is called in rcu pathwalk mode with nothing but rcu_read_lock() held. The dentry itself stays around for such a walker, but tracefs_d_release() drops its reference to the eventfs_inode when the dentry is killed, and release_ei() then frees it after a grace period of eventfs_srcu. An SRCU grace period doesn't wait for rcu_read_lock() sections, so the walker can read an eventfs_inode that is already gone.
With a pathwalk held up in tracefs_d_revalidate() while the dentry goes away:
BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90 Read of size 1 at addr ff1100010152d8d0 by task walker/97 Call Trace: <TASK> tracefs_d_revalidate+0x76/0x90 lookup_fast+0x320/0x640 path_lookupat+0x160/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 vfs_fstatat+0x4d/0x90 __do_sys_newfstatat+0xa0/0x100 do_syscall_64+0x10e/0x5e0 entry_SYSCALL_64_after_hwframe+0x77/0x7f [...] Allocated by task 1: __kmalloc_cache_noprof+0x249/0x560 eventfs_create_dir+0x7a/0x590 event_create_dir+0x2fb/0xcf0 trace_add_event_call+0xbf/0x150 [...] Freed by task 11: kfree+0x1db/0x5b0 srcu_invoke_callbacks+0x3a3/0x620 process_one_work+0x937/0x1810 worker_thread+0x4f1/0xd60
Before commit 8e556432477e ("eventfs: Use SRCU for freeing eventfs_inodes") release_ei() used call_rcu(), which covered the walker, while eventfs_iterate() needs the SRCU grace period. Wait for both and chain call_rcu() from the SRCU callback.
This page as .md · .json · in your agent: get_signal("CVE-2026-99173")
NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.