CVE-2026-99226 - Vulnerability Details

- keys: Avoid the owner account dereference in named keyring lookup

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:

Action:

Analysis

Impact

An oversight in the Linux kernel’s keyring subsystem can cause a use‑after‑free error when a named keyring is accessed while its owner account is changed on another CPU. The lookup function reads the user’s UID from a stale key_user pointer after that object has been freed, which can lead to a kernel crash or, if an attacker can control the freed memory, arbitrary execution in kernel mode. This flaw enables an attacker with local access to potentially elevate privileges or compromise the kernel.

Affected Systems

All Linux kernel implementations that have not yet incorporated the patch are affected. The CVE description does not list specific kernel releases, indicating that the issue is present in multiple earlier versions across Linux distributions. Any system running the kernel prior to the update that resolves this bug is vulnerable.

Risk and Exploitability

The EPSS score is not available and the vulnerability is not listed in CISA’s KEV catalog, but the nature of a use‑after‑free in kernel code suggests a high CVSS score and a dangerous local attack surface. Exploitation would require an attacker to trigger the race between a named keyring lookup and a privileged KEYCTL_CHOWN operation, a condition that is plausible on multithreaded systems. In the absence of a public exploit, the risk remains theoretical yet significant because of the kernel’s privileged execution context.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< 77249d4b1bb5ad43552b7023c4a0978937aa7a56
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< 0b865fa477d94ac96c26848aab1fd176397de3f6
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< 6763329f673d261641c79212abf773af77b2c922
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< aa03c8fb4334f14d218020f7431debf2b7766865
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< c9664f780f861dd9f11f120c7a03ed0993671ebb
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< b0830a26e2c3008a6e21863126b4a0e68b2761cd
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< 5c6a9512887a6cc694d594d9c0b57c0841d215b5
`2ea190d0a006ce5218baa6e798512652446a605a`	affected	< 40b12b93ae4ab9e22c3d571e9b09fd08afad53f6

Linux

affected

Version	Status	Constraints
`2.6.30`	affected	—
`0`	unaffected	< 2.6.30
`5.10.273`	unaffected	≤ 5.10.*
`5.15.224`	unaffected	≤ 5.15.*
`6.1.191`	unaffected	≤ 6.1.*
`6.6.161`	unaffected	≤ 6.6.*
`6.12.115`	unaffected	≤ 6.12.*
`6.18.60`	unaffected	≤ 6.18.*
`7.2.14`	unaffected	≤ 7.2.*
`7.3.1`	unaffected	≤ 7.3.*

No data.

Vendor Product Confidence Versions

Linux

100%

Version	Status	Scheme	Platform
`[2ea190d0a006ce5218baa6e798512652446a605a,77249d4b1bb5ad43552b7023c4a0978937aa7a56)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,0b865fa477d94ac96c26848aab1fd176397de3f6)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,6763329f673d261641c79212abf773af77b2c922)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,aa03c8fb4334f14d218020f7431debf2b7766865)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,c9664f780f861dd9f11f120c7a03ed0993671ebb)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,b0830a26e2c3008a6e21863126b4a0e68b2761cd)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,5c6a9512887a6cc694d594d9c0b57c0841d215b5)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,40b12b93ae4ab9e22c3d571e9b09fd08afad53f6)`	affected	generic	—

Linux

100%

Version	Status	Scheme	Platform
`2.6.30`	affected	semver	—
`[0,2.6.30)`	unaffected	generic	—
`[5.10.273,5.11.0)`	unaffected	semver	—
`[5.15.224,5.16.0)`	unaffected	semver	—
`[6.1.191,6.2.0)`	unaffected	semver	—
`[6.6.161,6.7.0)`	unaffected	semver	—
`[6.12.115,6.13.0)`	unaffected	semver	—
`[6.18.60,6.19.0)`	unaffected	semver	—
`[7.2.14,7.3.0)`	unaffected	semver	—
`[7.3.1,7.4.0)`	unaffected	semver	—

Linux

Linux Kernel

100%

Version	Status	Scheme	Platform
`[2ea190d0a006ce5218baa6e798512652446a605a,77249d4b1bb5ad43552b7023c4a0978937aa7a56)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,0b865fa477d94ac96c26848aab1fd176397de3f6)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,6763329f673d261641c79212abf773af77b2c922)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,aa03c8fb4334f14d218020f7431debf2b7766865)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,c9664f780f861dd9f11f120c7a03ed0993671ebb)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,b0830a26e2c3008a6e21863126b4a0e68b2761cd)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,5c6a9512887a6cc694d594d9c0b57c0841d215b5)`	affected	generic	—
`[2ea190d0a006ce5218baa6e798512652446a605a,40b12b93ae4ab9e22c3d571e9b09fd08afad53f6)`	affected	generic	—

Linux

Linux Kernel

100%

Version	Status	Scheme	Platform
`2.6.30`	affected	semver	—
`[0,2.6.30)`	unaffected	generic	—
`[5.10.273,5.11.0)`	unaffected	semver	—
`[5.15.224,5.16.0)`	unaffected	semver	—
`[6.1.191,6.2.0)`	unaffected	semver	—
`[6.6.161,6.7.0)`	unaffected	semver	—
`[6.12.115,6.13.0)`	unaffected	semver	—
`[6.18.60,6.19.0)`	unaffected	semver	—
`[7.2.14,7.3.0)`	unaffected	semver	—
`[7.3.1,7.4.0)`	unaffected	semver	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the latest Linux kernel patch that fixes the keyring use‑after‑free bug.
Reboot the system after applying the patch to ensure all kernel instances use the updated code.
If a patch is unavailable, audit and restrict the use of the keyctl_chown system call by adjusting file system permissions or disabling the keyrings feature until the fix is deployed.

Generated by OpenCVE AI on November 2, 2026 at 18:08 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0b865fa477d94ac96c26848aab1fd176397de3f6
https://git.kernel.org/stable/c/40b12b93ae4ab9e22c3d571e9b09fd08afad53f6
https://git.kernel.org/stable/c/5c6a9512887a6cc694d594d9c0b57c0841d215b5
https://git.kernel.org/stable/c/6763329f673d261641c79212abf773af77b2c922
https://git.kernel.org/stable/c/77249d4b1bb5ad43552b7023c4a0978937aa7a56
https://git.kernel.org/stable/c/aa03c8fb4334f14d218020f7431debf2b7766865
https://git.kernel.org/stable/c/b0830a26e2c3008a6e21863126b4a0e68b2761cd
https://git.kernel.org/stable/c/c9664f780f861dd9f11f120c7a03ed0993671ebb

History

Mon, 02 Nov 2026 20:30:00 +0000

Type	Values Removed	Values Added
First Time appeared		Linux linux
Vendors & Products		Linux linux

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		https://git.kernel.org/stable/c/0b865fa477d94ac96c26848aab1fd176397de3f6 https://git.kernel.org/stable/c/40b12b93ae4ab9e22c3d571e9b09fd08afad53f6 https://git.kernel.org/stable/c/5c6a9512887a6cc694d594d9c0b57c0841d215b5 https://git.kernel.org/stable/c/6763329f673d261641c79212abf773af77b2c922 https://git.kernel.org/stable/c/77249d4b1bb5ad43552b7023c4a0978937aa7a56 https://git.kernel.org/stable/c/aa03c8fb4334f14d218020f7431debf2b7766865 https://git.kernel.org/stable/c/b0830a26e2c3008a6e21863126b4a0e68b2761cd https://git.kernel.org/stable/c/c9664f780f861dd9f11f120c7a03ed0993671ebb

Subscriptions

Linux Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

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

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

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

Link: CVE-2026-99226

Vulnrichment

No data.

NVD

Status : Received

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

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

Link: CVE-2026-99226

Redhat

No data.

OpenCVE Enrichment

Updated: 2026-11-02T20:15:15Z

Weaknesses

CWE-362
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-416
Use After Free

Impact

Affected Systems

Risk and Exploitability

Tracking

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