Bug 2525367 (CVE-2026-80673)

Summary: CVE-2026-80673 kernel: ntfs: bound the look-ahead attribute-list entry in ntfs_external_attr_find()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's NTFS file system driver. An attacker can craft a malicious on-disk attribute list that, when processed, causes an out-of-bounds read. This occurs because a look-ahead entry in the attribute list is not properly validated, allowing data to be read beyond the allocated buffer. This vulnerability can lead to information disclosure when an inode is read.
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Description OSIDB Bzimport 2026-08-28 07:41:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ntfs: bound the look-ahead attribute-list entry in ntfs_external_attr_find()

When resolving an attribute lookup with a non-zero @lowest_vcn,
ntfs_external_attr_find() peeks at the next $ATTRIBUTE_LIST entry to
decide whether to keep searching, but bounds that not-yet-validated
entry only with "(u8 *)next_al_entry + 6 < al_end" (which proves just
bytes 0..6 are in range) and "(u8 *)next_al_entry + length <= al_end"
with an attacker-controlled, non-8-aligned length. It then reads
next_al_entry->lowest_vcn (an __le64 at offset 8) and the name at
next_al_entry->name_offset, both of which can lie past al_end -- the
exact end of the kvmalloc'd attribute-list buffer (allocated at the
on-disk attr_list_size, no rounding). A crafted on-disk $ATTRIBUTE_LIST
whose last entry sits a few bytes before al_end therefore yields a slab
out-of-bounds read when the inode is read.

Validate the look-ahead entry with ntfs_attr_list_entry_is_valid() (added
in patch 1/3) before dereferencing lowest_vcn and the name, so the same
fixed-header, length and name bounds the main attribute-list walk uses now
guard this read too.
Comment 1 gkamathe 2026-08-31 06:34:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082848-CVE-2026-80673-fe8f@gregkh/T