CVE-2025-40307
In the Linux kernel, the following vulnerability has been resolved: exfat: validate cluster allocation bits of the allocation bitmap syzbot created an exfat image with cluster bits not set for the allocation bitmap. exfat-fs reads and uses the allocation bitmap without checking this. The problem is that if the start cluster of the allocation bitmap is 6, cluster 6 can be allocated when creating a directory with mkdir. exfat zeros out this cluster in exfat_mkdir, which can delete existing entries. This can reallocate the allocated entries. In addition, the allocation bitmap is also zeroed out, so cluster 6 can be reallocated. This patch adds exfat_test_bitmap_range to validate that clusters used for the allocation bitmap are correctly marked as in-use.
Affected versions
Linux kernel versions
5.7
and later are affected. Fixed in
6.12.58,
6.17.8,
6.18
and their respective stable series.
References
The following references provide additional information about CVE-2025-40307 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/13c1d24803d5b0446b3f6f0fdd67e07ac1fdc7bf
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PatchKernel patch commithttps://git.kernel.org/stable/c/6bc58b4c53795ab5fe00648344aa7d9d61175f90
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PatchKernel patch commithttps://git.kernel.org/stable/c/79c1587b6cda74deb0c86fc7ba194b92958c793c
Frequently asked questions
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What is CVE-2025-40307?
CVE-2025-40307 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.7 onward and has been patched in 6.12.58, 6.17.8 and 6.18. CVE-2025-40307 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2025-40307?
Yes — CVE-2025-40307 has been patched. Fixed versions include 6.12.58, 6.17.8 and 6.18. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2025-40307 actively exploited?
No — CVE-2025-40307 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.