Description
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
Published: 2026-11-02
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Mon, 02 Nov 2026 18:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362
CWE-416

Mon, 02 Nov 2026 16:15:00 +0000

Type Values Removed Values Added
Description 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
Title keys: Avoid the owner account dereference in named keyring lookup
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-11-02T16:06:35.362Z

Reserved: 2026-09-25T10:25:14.402Z

Link: CVE-2026-99226

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-02T16:17:47.233

Modified: 2026-11-02T16:17:47.233

Link: CVE-2026-99226

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-02T18:15:14Z

Weaknesses