Live › vulnerability › CVE-2026-99226
A race in the Linux kernel's keyring code lets a named session-keyring join read an account structure that a privileged chown has already freed. The read is a use-after-free, which can crash the kernel or, if an attacker controls the freed memory, may allow further impact the sources do not describe.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-11-02 16:24 UTC. All times on this page are UTC.
Systems running affected Linux kernel builds where local users can create or join named keyrings. The sources describe a local race that needs a privileged chown on another CPU, so exposure depends on the kernel version and on who can run keyctl on the host. unknown whether the sources list a specific affected range.
No product ranges from the sources yet.
uname -r and compare it against the fixed kernel versions in the NVD entry.Unknown from the sources.
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:
keys: Avoid the owner account dereference in named keyring lookup
Named keyring lookup must keep the storage containing the owner UID alive through the namespace mapping check. find_keyring_by_name() reads keyring->user->uid under keyring_name_lock, but that lock protects the keyring's name entry and allocation, not its separate key_user.
A named session-keyring join can overlap a privileged KEYCTL_CHOWN on another CPU. If the keyring holds the last reference to its old dynamic key_user and the ownership transfer succeeds, the following ordering is possible:
Named join Chown
find_keyring_by_name() keyctl_chown_key()
read_lock(keyring_name_lock) down_write(key->sem)
load old keyring->user
replace key->user and key->uid
up_write(key->sem)
key_put(key)
key_user_put(old user): free
read old user->uid
read_unlock(keyring_name_lock)
Chown neither takes keyring_name_lock nor key_session_mutex, so it can free the old account between the pointer load and the UID read. The lookup then reads freed memory even though the keyring itself is alive.
Use keyring->uid for the mapping check. key_alloc() initializes this inline owner UID and keyctl_chown_key() updates it on chown. The existing name lock keeps its containing keyring allocated throughout the check, so lookup no longer depends on the account's lifetime. This also matches the owner UID used by the permission check.
KASAN report as below:
BUG: KASAN: slab-use-after-free in find_keyring_by_name+0x577/0x5d0
Read of size 4 at addr ffff8881128ae2ec by task keycase/500
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