CVE-2026-74723
Received Received - Intake

Buffer Overflow in Linux Kernel Btrfs LZO Compression

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: lzo: reject inline extents without valid headers [BUG] For a crafted btrfs image, the following KASAN can be triggered when reading an inline lzo compressed file extent: BUG: KASAN: slab-out-of-bounds in lzo_decompress+0x57d/0x700 Read of size 4 at addr ffff888006f2e644 by task btrfs_lzo_inlin/77 Call Trace: <TASK> dump_stack_lvl+0x5b/0x70 print_report+0xd1/0x610 kasan_report+0xe0/0x110 __asan_report_load_n_noabort+0x13/0x20 lzo_decompress+0x57d/0x700 btrfs_decompress+0x140/0x1c0 uncompress_inline+0x147/0x1b0 btrfs_get_extent+0xb23/0x10a0 btrfs_do_readpage.constprop.0+0x538/0x1ac0 btrfs_readahead+0x32f/0x5f0 read_pages+0x16f/0x850 page_cache_ra_unbounded+0x296/0x490 do_page_cache_ra+0xd9/0x130 page_cache_sync_ra+0x3ee/0x6f0 filemap_get_pages+0x306/0x15c0 filemap_read+0x329/0xd00 btrfs_file_read_iter+0x1f8/0x2b0 vfs_read+0x4ef/0x720 ksys_read+0xf8/0x1d0 __x64_sys_read+0x71/0xb0 x64_sys_call+0x1ab0/0x1b70 do_syscall_64+0x61/0x470 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK> [CAUSE] For an inline lzo compressed file extent, there should always be one lzo header, recording the total length of the compressed data, followed by one segment header, recording the compressed lzo payload. But if a crafted inline lzo compressed file extent contains only an lzo header, without the segment header or payload, lzo_decompress() will still try to read the segment header, causing a read beyond the item boundary. Furthermore if the inline lzo compressed file extent is the first item of the leaf, it will be at the extent buffer boundary. The above out-of-boundary read will go beyond the extent buffer boundary, triggering the above KASAN report. [FIX] Validate the total length of the inlined lzo compressed file extent, to make sure there is at least one LZO header and one segment header, and a non-zero payload. [ Rework the commit message to remove slop ]

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74723
EUVD
EUVD-2026-64410

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel btrfs *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel's btrfs filesystem involves a flaw in handling LZO-compressed inline file extents. When a crafted btrfs image contains an inline LZO compressed file extent without a valid header, it triggers a slab-out-of-bounds read error in the lzo_decompress function. This occurs because the code attempts to read a segment header that doesn't exist, leading to memory corruption.

Detection Guidance

This vulnerability is specific to the Linux kernel's btrfs filesystem with LZO compression. Detection requires checking for out-of-bounds reads in btrfs operations. Monitor kernel logs for KASAN reports like 'slab-out-of-bounds in lzo_decompress'. Use 'dmesg | grep -i kasan' to check for such errors. Ensure your kernel is updated to a patched version.

Impact Analysis

This vulnerability could allow an attacker to cause a denial of service by crashing the system through a kernel panic. It may also potentially enable arbitrary code execution if exploited successfully. Systems using btrfs with LZO compression are at risk when processing malicious filesystem images.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for this btrfs LZO compression issue. Avoid using btrfs with LZO compression for untrusted files until patched. Monitor filesystem operations closely for signs of exploitation or crashes.

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