CVE-2026-64322: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: udf: validate sparing table length as an entry count, not a byte count udf_load_sparable_map() accepts a sparing table when sizeof(*st) + le16_to_cpu(st->reallocationTableLen) > sb->s_blocksize is false, i.e. it treats reallocationTableLen as a number of BYTES that must fit in the block. But the table is walked as an array of 8-byte sparingEntry elements: for (i = 0; i < le16_to_cpu(st->reallocationTableLen); i++) { struct sparingEntry *entry = &st->mapEntry[i]; ... entry->origLocation ... } in udf_get_pblock_spar15() and udf_relocate_blocks(). A reallocationTableLen of N therefore passes the check whenever sizeof(*st) + N <= blocksize, yet the consumers index sizeof(*st) + N * sizeof(struct sparingEntry) bytes -- up to ~8x the block. On a crafted UDF image this is an out-of-bounds read in udf_get_pblock_spar15(); udf_relocate_blocks() additionally feeds the same length to udf_update_tag(), whose crc_itu_t() reads far past the block, and its memmove() through st->mapEntry[] is an out-of-bounds write. Validate reallocationTableLen as the entry count it is, with struct_size().

Affected products

• Linux Linux Kernel: from 2.6.32.60, before 2.6.33 (fixed in 2.6.33); from 2.6.34.14, before 2.6.35 (fixed in 2.6.35); from 3.0.37, before 3.1 (fixed in 3.1); from 3.2.23, before 3.3 (fixed in 3.3); from 3.4.5, before 3.5 (fixed in 3.5); from 3.5.1, before 5.10.261 (fixed in 5.10.261); …

Published 2026-07-25. Last modified 2026-09-04.