CVE-2026-64323

High

Description

In the Linux kernel, the following vulnerability has been resolved: udf: validate VAT header length against the VAT inode size udf_load_vat() takes the virtual partition's start offset straight from the on-disk VAT 2.0 header without checking it against the VAT inode size: map->s_type_specific.s_virtual.s_start_offset = le16_to_cpu(vat20->lengthHeader); map->s_type_specific.s_virtual.s_num_entries = (sbi->s_vat_inode->i_size - map->s_type_specific.s_virtual.s_start_offset) >> 2; lengthHeader is a fully attacker-controlled 16-bit value. If it exceeds the VAT inode size, the s_num_entries subtraction underflows to a huge count, which defeats the "block > s_num_entries" bound in udf_get_pblock_virt15(); and on the ICB-inline path that function reads ((__le32 *)(iinfo->i_data + s_start_offset))[block] so a large s_start_offset indexes past the inode's in-ICB data. Mounting a crafted UDF image with a virtual (VAT) partition then triggers an out-of-bounds read. Reject a VAT whose header length does not leave room for at least one entry within the VAT inode.

SeverityHigh
CVSS7.1
Exploit probability—
ProductLinux Kernel
PublishedJul 25, 2026
First seenJul 25, 2026

How to fix

Update
  • linux linux_kernel5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4 or later

Affected products

ProductAffected versionsFixed in
linux linux_kernel2.6.26 ≤ v < 5.10.261, 5.11 ≤ v < 5.15.212, 5.16 ≤ v < 6.1.178, 6.2 ≤ v < 6.6.145, 6.7 ≤ v < 6.12.96, 6.13 ≤ v < 6.18.39, 6.19 ≤ v < 7.1.45.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4

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CVE-2026-64323 · Linux Kernel · Dark Radar