Linux Kernel up to 6.18.52/7.2.6/7.3-rc1 btrfs zstd_get_workspace race condition

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.17+

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.18.52/7.2.6/7.3-rc1. This vulnerability affects the function zstd_get_workspace of the component btrfs. This manipulation causes race condition. This vulnerability is handled as CVE-2026-98079. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.52/7.2.6/7.3-rc1. It has been declared as critical. Affected by this vulnerability is the function zstd_get_workspace of the component btrfs. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: btrfs: zstd: fix lost wakeup when waiting for a workspace A writer can sleep forever in zstd_get_workspace() even though a workspace is free. When zstd_alloc_workspace() fails, the task is queued on zwsm->wait and schedules unconditionally, never re-testing the pool. zstd_put_workspace() publishes the workspace and then calls cond_wake_up(), which only wakes when a sleeper is already visible, so a workspace returned between the failed allocation and prepare_to_wait() wakes nobody. The window is wide: zstd_alloc_workspace() goes through kvmalloc() and may enter reclaim. Only a max level workspace triggers the wakeup and one is deliberately kept allocated as the fallback every waiter waits for, so once its wakeup is lost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens to return one. Re-check the pool after prepare_to_wait() has published the waiter, and use the workspace if one turned up.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-98079 since 09/25/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/25/2026).

Upgrading to version 6.18.53, 7.2.7 or 7.3-rc2 eliminates this vulnerability. Applying the patch d8f57049521948df5f50797141472fbbed3b0723/0de9f31d447ae71ab08c7850a321682f8d2907c3/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
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 6.18.53/7.2.7/7.3-rc2
Patch: d8f57049521948df5f50797141472fbbed3b0723/0de9f31d447ae71ab08c7850a321682f8d2907c3/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7

Timelineinfo

09/25/2026 Advisory disclosed
09/25/2026 +0 days CVE reserved
09/25/2026 +0 days VulDB entry created
09/25/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98079 (🔒)
GCVE (CVE): GCVE-0-2026-98079
GCVE (VulDB): GCVE-100-410281

Entryinfo

Created: 09/25/2026 16:24
Changes: 09/25/2026 16:24 (59)
Complete: 🔍
Cache ID: 216::103

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