Linux Kernel up to 6.18.53/7.2.7/7.3-rc3 btrfs btrfs_rebuild_free_space_tree race condition

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k0.00

Summaryinfo

A vulnerability marked as very critical has been reported in Linux Kernel up to 6.18.53/7.2.7/7.3-rc3. Affected is the function btrfs_rebuild_free_space_tree of the component btrfs. The manipulation leads to race condition. This vulnerability is referenced as CVE-2026-98244. The attack can only be performed from a local environment. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.53/7.2.7/7.3-rc3. It has been rated as very critical. This issue affects the function btrfs_rebuild_free_space_tree of the component btrfs. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: btrfs: clear free space tree creation state on rebuild failure btrfs_rebuild_free_space_tree() sets BTRFS_FS_CREATING_FREE_SPACE_TREE before rebuilding the free space tree. Several error paths return without clearing this flag. The transaction restart failure path can leave the flag set on a live filesystem, causing delayed reference processing to be skipped. Clear it on all free space tree rebuild failure paths. Keep BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED set, since a failed rebuild leaves the free space tree untrusted. Callers must fall back to extent-tree caching.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-98244 since 09/25/2026. The exploitation is known to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/06/2026).

Upgrading to version 6.18.54, 7.2.8 or 7.3-rc4 eliminates this vulnerability. Applying the patch a32bedab8ece9d1f90a1476a5b486a1804dc78ba/b1df2997d0cd2be7bef7b4ab64ccfd1019dedc81/3565893cc72cdf6b795cf6a33e7ff9605322334d is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.4

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

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 6.18.54/7.2.8/7.3-rc4
Patch: a32bedab8ece9d1f90a1476a5b486a1804dc78ba/b1df2997d0cd2be7bef7b4ab64ccfd1019dedc81/3565893cc72cdf6b795cf6a33e7ff9605322334d

Timelineinfo

09/25/2026 CVE reserved
10/06/2026 +11 days Advisory disclosed
10/06/2026 +0 days VulDB entry created
10/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98244 (🔒)
GCVE (CVE): GCVE-0-2026-98244
GCVE (VulDB): GCVE-100-414215

Entryinfo

Created: 10/06/2026 13:44
Changes: 10/06/2026 13:44 (59)
Complete: 🔍
Cache ID: 216::103

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