Kernel memory compromise via stale JFS bmap pointer
Published Dec 24, 2025 · Updated Dec 24, 2025
Double-free in the Linux kernel JFS remount path allows local users to corrupt kernel memory through a crafted JFS image. dbUnmount frees the in-memory bmap but leaves the superblock pointer non-NULL, so a failed dbMount or diMount during jfs_remount causes a later remount or unmount to free the same allocation again. Reaching the flaw requires local filesystem operations on attacker-controlled JFS media; successful exploitation grants kernel-memory read or write access or crashes the system.
Summary
What happened
Double-free in the Linux kernel JFS remount path allows local users to corrupt kernel memory through a crafted JFS image. dbUnmount frees the in-memory bmap but leaves the superblock pointer non-NULL, so a failed dbMount or diMount during jfs_remount causes a later remount or unmount to free the same allocation again. Reaching the flaw requires local filesystem operations on attacker-controlled JFS media; successful exploitation grants kernel-memory read or write access or crashes the system.
The record
- CVE
- CVE-2023-54127
- Published
- Dec 24, 2025
- Updated
- Dec 24, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 24, 2025CVE publishedPublication date reported by the CVE source.
- Dec 24, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2f7a36448f51d08d3a83f1514abcca4b680bcd3c
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6f8b34458948ffca2fe90cd8c614e3fa2ebe0b27
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <798c5f6f98bc9045593d4b3a65c32f05d97bd0e6
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <aa5b019a3e0f7f54f4e5370c1af827f6b00fd26b
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <aef6507e85475e30831c30405d785c7ed976ea4a
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b12ccbfdf6539ef0157868f69fcae0b7f7a072b3
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cade5397e5461295f3cb87880534b6a07cafa427
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f71c4bb3ec08dfcbd201350a6a0a914c4e6a9e3f
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- syzbot reproducer for invalid-free in dbUnmountproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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