Linux Kernel up to 6.18.51/7.2.5 md-llbitmap llbitmap_destroy use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.00-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.51/7.2.5. It has been rated as very critical. This vulnerability affects the function llbitmap_destroy of the component md-llbitmap. The manipulation leads to use after free. This vulnerability is referenced as CVE-2026-90276. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.51/7.2.5 and classified as very critical. This issue affects the function llbitmap_destroy of the component md-llbitmap. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: md/md-llbitmap: stop daemon timer rearm on destroy llbitmap_destroy() deletes pending_timer before flushing md_llbitmap_io_wq. However, daemon_work can still be queued or running after the timer has been deleted, and the daemon path can arm pending_timer again when it finds dirty chunks that are not ready to flush yet. If that happens during teardown, pending_timer can remain armed after llbitmap is freed and later dereference freed memory. Add a BITMAP_SHUTDOWN bit to llbitmap->flags, set it before deleting the timer, and make the timer and daemon paths stop queueing or rearming work once teardown starts. Cancel daemon_work before flushing the shared workqueue so no already queued daemon instance can race with the free. Use timer_shutdown_sync() so a daemon instance that passed the shutdown check before teardown cannot rearm the timer afterward. BITMAP_SHUTDOWN is a runtime-only state. Mask it out when reading and updating the llbitmap superblock so the shutdown state is never loaded from disk or persisted to disk.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-90276 since 09/11/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/17/2026).

Upgrading to version 6.18.52, 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch c55aa6c17f019b6296952d336939891efa084c06/bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c/5553d64e01d9a995be6c3de38501c6dd4ceede3b is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.52/7.2.6/7.3-rc1
Patch: c55aa6c17f019b6296952d336939891efa084c06/bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c/5553d64e01d9a995be6c3de38501c6dd4ceede3b

Timelineinfo

09/11/2026 CVE reserved
09/17/2026 +6 days Advisory disclosed
09/17/2026 +0 days VulDB entry created
09/17/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-90276 (🔒)
GCVE (CVE): GCVE-0-2026-90276
GCVE (VulDB): GCVE-100-406805

Entryinfo

Created: 09/17/2026 21:16
Changes: 09/17/2026 21:16 (59)
Complete: 🔍
Cache ID: 216::103

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