CVE-2026-89525

Summary

In the Linux kernel, the following vulnerability has been resolved:

udf: reject VAT indexes equal to the entry count

UDF 1.50 virtual partition mapping uses the VAT as an array of physical block mappings. s_num_entries stores the number of entries in that array, not the highest valid index. The valid VAT indexes are therefore below s_num_entries.

udf_get_pblock_virt15() currently rejects only indexes greater than s_num_entries. A crafted image can request index s_num_entries, pass the bounds check, and make the kernel read one entry past the allocated VAT table.

Change the check to reject block >= s_num_entries, so the count is handled as an exclusive upper bound.

A crafted UDF image reproduced this on origin/master commit 0e35b9b6ec0ffcc5e23cbdec09f5c622ad532b53 with a KASAN slab-out-of-bounds report in udf_get_pblock_virt15().

Trail of Bits has a reproducer that triggers kernel panic demonstrating the bug, and can share it if needed.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9193368408d792cec2057628d87862140fb1ce1caffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < b95c33a4e743874f1b0a45bf2aaa4da553552bd1affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1bd7947f1463c21edafa256d0fbec5b99215e2b6affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cac0cb07f29ccfb373fd4a36c81e908ef3ce608caffected
LinuxLinux2.6.12affected
LinuxLinux0 < 2.6.12unaffected
LinuxLinux6.12.109 <= 6.12.*unaffected
LinuxLinux6.18.50 <= 6.18.*unaffected
LinuxLinux7.2.4 <= 7.2.*unaffected
LinuxLinux7.3-rc1 <= *unaffected

Weaknesses

References