# CVE-2026-99226: keys: Avoid the owner account dereference in named keyring lookup

CVE-2026-99226 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99226, released November 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99226
- Priority: Routine
- CVSS: 4.7 (Moderate)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 2, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99226

## 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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-1 | [DEBIAN-CVE-2026-99226](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99226.md) | Nov 3, 2026 |
| Linux | linux Debian 14 | 7.2.14-1 | [DEBIAN-CVE-2026-99226](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99226.md) | Nov 3, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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