CVE-2026-64322
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().
CSIRTS triage
- What
- This vulnerability relates to improper validation of sparing table length in the UDF filesystem.
- Who is affected
- Deployments using the UDF filesystem.
- Urgency
- Remediation is important to ensure filesystem integrity, with no current exploitation reported.
- Action
- Apply the patch for CVE-2026-64322.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.16% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 6% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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