---
id: CVE-2026-64322
title: "In the Linux kernel, the following vulnerability has been resolved:\n\nudf: validate sparing table length as an entry count, not a byte count\n\nudf_load_sparable_map() accepts a sparing table when\n\n\tsizeof(*st) + le16_to_cpu(st->reallocatio…"
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nudf: validate sparing table length as an entry count, not a byte count\n\nudf_load_sparable_map() accepts a sparing table when\n\n\tsizeof(*st) + le16_to_cpu(st->reallocatio…"
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
published: '2026-07-25'
updated: '2026-07-27'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64322'
references:
  - url: 'https://git.kernel.org/stable/c/04f4599a9efb90992d072a814960edf0cd62805d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2a219acb2ce674d99bbd1b7b35ed8c384dac7200'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2d726135099313958f8975532a2e15322ff150ce'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3ec997bd5508e9b25210b5bbec89031629cdb093'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7285276aa50d2839afb5957ffd491ad282dc8f72'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7f7774b9da0ef17b87bfa238cf966ad0b3376150'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eeb0f3e193f8e523d03e4c9e084f6b4875f50e8e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00169
epssPercentile: 0.05422
ingestedAt: '2026-07-27T06:16:50.529Z'
---

## Overview

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().

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.