Live › vulnerability › CVE-2026-99175
Go to dashboardA race in the kernel's fsnotify connector teardown can let a new mark be inserted during detach, so a concurrent unprivileged read of inotify fdinfo dereferences a NULL inode and triggers a KASAN null-pointer crash. The sources describe a kernel memory-safety bug with a crash on the read path; they do not say whether code execution is possible.
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 without the fsnotify teardown fix, where unprivileged local users can read inotify fdinfo (/proc/<pid>/fdinfo) while watches are being removed. The sources do not say which kernel versions are affected or whether default distributions expose the path. Hosts that do not run untrusted local users have lower exposure.
No product ranges from the sources yet.
uname -r and compare against the kernel versions listed in the NVD record for CVE-2026-99175 (unknown in the sources provided)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:
fsnotify: prevent mark additions during connector teardown
fsnotify_destroy_marks() keeps a reference to its current mark while it drops conn->lock to destroy the mark. This stabilizes the forward-walk cursor, but does not prevent a new mark from being inserted before it. For example, an inotify watch re-added after IN_IGNORED sorts before the old, detached mark for the same group. The walk can miss the replacement and then detach the entire connector from the object.
The replacement is still on its group's marks_list and, for inotify, in the watch IDR. The group mutex no longer protects the connector's object from disappearing. An unprivileged fdinfo read racing the final detach can consequently call igrab(NULL):
BUG: KASAN: null-ptr-deref in igrab+0x24/0x100 Write of size 4 at addr 0000000000000148 Call Trace: igrab+0x24/0x100 inotify_show_fdinfo+0x1dc/0x5e0 seq_show+0x397/0x690
Set a DESTROYING flag under conn->lock before starting the walk, and reject new marks on that connector with -ENOENT. The existing add-mark error paths undo the temporary group-list entry and the backend's watch allocation. Do not wait for teardown while holding the group mutex, which the destroyer needs. Once the old connector is detached, an add can install a fresh connector as before.
This closes the insertion race for all object types using the common connector teardown, without changing the mark reference or SRCU lifetime rules.
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