CVE-2025-40307
exfat: validate cluster allocation bits of the allocation bitmap
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.
| Vendor | linux |
| Product | linux |
| Ecosystems | |
| Industries | Technology |
| Published | Dec 8, 2025 |
| Last Updated | May 11, 2026 |
Get instant alerts for linux linux
Be the first to know when new unknown vulnerabilities affecting linux linux are published — delivered to Slack, Telegram or Discord.