Kernel memory corruption via lockspace teardown race
Published Dec 4, 2025 · Updated Aug 5, 2026
Use-after-free in the Linux kernel GFS2 subsystem allows local users to corrupt kernel memory during lockspace teardown. The gdlm_put_lock() path frees a glock after DFL_UNMOUNT is set but before lockspace release completes, allowing late gdlm_ast() or gdlm_bast() callbacks to dereference freed memory. Reachability requires local low-privileged access and a high-complexity timing window during GFS2 unmount or withdrawal; successful corruption compromises the host kernel.
Summary
What happened
Use-after-free in the Linux kernel GFS2 subsystem allows local users to corrupt kernel memory during lockspace teardown. The gdlm_put_lock() path frees a glock after DFL_UNMOUNT is set but before lockspace release completes, allowing late gdlm_ast() or gdlm_bast() callbacks to dereference freed memory. Reachability requires local low-privileged access and a high-complexity timing window during GFS2 unmount or withdrawal; successful corruption compromises the host kernel.
The record
- CVE
- CVE-2025-40242
- Published
- Dec 4, 2025
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 4, 2025CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=01eb3106f43335fdc02111358dae80a5c3fd324d
- Affected versionversion=02e838963fdaa6ce8570b5389aecdc6cf1fb40b0
- Affected versionversion=2225a5cd2fbc2ef0e0f78e585db3844f60416a39
- Affected versionversion=3554b46204e67333e1fb8be0e93936fb08267c80
- Affected versionversion=4.14.247 <4.15
- Affected versionversion=4.19.207 <4.20
- Affected versionversion=4.4.284 <4.5
- Affected versionversion=4.9.283 <4.10
- Affected versionversion=5.10.67 <5.11
- Affected versionversion=5.13.19 <5.14
- Affected versionversion=5.14.6 <5.15
- Affected versionversion=5.15
- Affected versionversion=5.4.148 <5.5
- Affected versionversion=5cff77b9827a956d076168b56775aad23bce87e4
- Affected versionversion=6aa628c45875e7b8cca81ed9447a12a0e8f3504a
- Affected versionversion=8deedce385d220f90e435f534d71d27526273515
- Affected versionversion=a97e75203733be0a4263a78fb7b29352be150c1c
- Affected versionversion=d1340f80f0b8066321b499a376780da00560e857 <279bde3bbb0ac0bad5c729dfa85983d75a5d7641
- Affected versionversion=d1340f80f0b8066321b499a376780da00560e857 <28c4d9bc0708956c1a736a9e49fee71b65deee81
- Affected versionversion=d1340f80f0b8066321b499a376780da00560e857 <4913592a3358f6ec366b8346b733d5e2360b08e1
- Affected versionversion=d1340f80f0b8066321b499a376780da00560e857 <5fdc1474e678eea1700aa266c0b7c2c96f81dd0d
- Affected versionversion=d1340f80f0b8066321b499a376780da00560e857 <64c61b4ac645222fa7b724cef616c1f862a72a40
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What is affected?
Published CVSS scores
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Attacks
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