Linux Kernel up to 7.1.8 btrfs lzo_decompress out-of-bounds

Summaryinfo

A vulnerability described as very critical has been identified in Linux Kernel up to 7.1.8. Impacted is the function lzo_decompress of the component btrfs. The manipulation results in out-of-bounds. This vulnerability is identified as CVE-2026-74723. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.8. It has been classified as very critical. Affected is the function lzo_decompress of the component btrfs. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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 ]

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-74723 since 08/15/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation needs additional levels of successful authentication. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/22/2026).

Upgrading to version 7.1.9 eliminates this vulnerability. Applying the patch fc50b475ad27f50b4dcc98fc4c44e8802bc1b248/0fa78ef637deb5dbe341582f88553a4bce496de0 is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-64410). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.1.6
• 7.1.7
• 7.1.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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