CVE-2025-40265
BaseFortify
Publication date: 2025-12-04
Last updated on: 2025-12-04
Assigner: kernel.org
Description
Description
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability in the Linux kernel relates to the vfat filesystem driver where missing checks on the return value of sb_min_blocksize() could cause a kernel panic. Specifically, when emulating an NVMe device on QEMU with both logical and physical block sizes set to 8 KiB but without formatting, the kernel would panic during early boot while trying to mount a vfat filesystem. This happens because the kernel fails to properly handle certain block size conditions, leading to a crash.
How can this vulnerability impact me? :
This vulnerability can cause a kernel panic during the early boot stage when mounting a vfat filesystem under specific conditions (emulated NVMe device with 8 KiB block sizes without format). This results in system instability or denial of service as the system crashes and cannot continue booting properly.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by monitoring kernel logs for specific error messages related to mounting vfat filesystems on nvme devices with unusual block sizes. Look for kernel panic messages or errors such as 'unable to set blocksize', 'unsupported/invalid hardware sector size 8192', or kernel BUGs during early boot or mount attempts. Commands to check kernel logs include: 'dmesg | grep -i "unable to set blocksize"', 'dmesg | grep -i "kernel BUG"', or 'journalctl -k | grep -i vfat'.
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include avoiding mounting vfat filesystems on nvme devices configured with both logical_block_size and physical_block_size set to 8 KiB without proper formatting. Additionally, update the Linux kernel to a version where this vulnerability is fixed, as the issue has been resolved in a kernel patch addressing missing sb_min_blocksize() return value checks.