{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74723","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-15T05:44:03.929Z","datePublished":"2026-08-22T15:33:15.196Z","dateUpdated":"2026-08-25T05:42:03.469Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-25T05:42:03.469Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: lzo: reject inline extents without valid headers\n\n[BUG]\nFor a crafted btrfs image, the following KASAN can be triggered when\nreading an inline lzo compressed file extent:\n\n  BUG: KASAN: slab-out-of-bounds in lzo_decompress+0x57d/0x700\n  Read of size 4 at addr ffff888006f2e644 by task btrfs_lzo_inlin/77\n\n  Call Trace:\n   <TASK>\n   dump_stack_lvl+0x5b/0x70\n   print_report+0xd1/0x610\n   kasan_report+0xe0/0x110\n   __asan_report_load_n_noabort+0x13/0x20\n   lzo_decompress+0x57d/0x700\n   btrfs_decompress+0x140/0x1c0\n   uncompress_inline+0x147/0x1b0\n   btrfs_get_extent+0xb23/0x10a0\n   btrfs_do_readpage.constprop.0+0x538/0x1ac0\n   btrfs_readahead+0x32f/0x5f0\n   read_pages+0x16f/0x850\n   page_cache_ra_unbounded+0x296/0x490\n   do_page_cache_ra+0xd9/0x130\n   page_cache_sync_ra+0x3ee/0x6f0\n   filemap_get_pages+0x306/0x15c0\n   filemap_read+0x329/0xd00\n   btrfs_file_read_iter+0x1f8/0x2b0\n   vfs_read+0x4ef/0x720\n   ksys_read+0xf8/0x1d0\n   __x64_sys_read+0x71/0xb0\n   x64_sys_call+0x1ab0/0x1b70\n   do_syscall_64+0x61/0x470\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n   </TASK>\n\n[CAUSE]\nFor an inline lzo compressed file extent, there should always be one lzo\nheader, recording the total length of the compressed data, followed by\none segment header, recording the compressed lzo payload.\n\nBut if a crafted inline lzo compressed file extent contains only an lzo\nheader, without the segment header or payload, lzo_decompress() will\nstill try to read the segment header, causing a read beyond the item\nboundary.\n\nFurthermore if the inline lzo compressed file extent is the first item\nof the leaf, it will be at the extent buffer boundary. The above\nout-of-boundary read will go beyond the extent buffer boundary,\ntriggering the above KASAN report.\n\n[FIX]\nValidate the total length of the inlined lzo compressed file extent, to\nmake sure there is at least one LZO header and one segment header, and a\nnon-zero payload.\n\n[ Rework the commit message to remove slop ]"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - On storage servers exporting a btrfs volume via nfsd or ksmbd, remote client read I/O reaches uncompress_inline→lzo_decompress on the server kernel; crafted inline LZO extents in a mounted image are parsed without local syscall access.\nAC:L - A btrfs image with an inline LZO extent containing only the 4-byte total header deterministically drives get_unaligned_le32 past the kmalloc copy in lzo_decompress(); tree-checker skips compressed-inline validation so mount succeeds and a normal read triggers the slab OOB.\nPR:N - Triggering requires only read access to exported btrfs content (nfsd/ksmbd read, loop-mount with CAP_SYS_ADMIN in a user namespace, or udisks-assisted mount); creating the malformed metadata needs offline image crafting, not init-namespace root on the victim.\nUI:N - Exploitation is the attacker's own read against an already-mounted/exported btrfs volume containing the crafted extent; no separate victim must mount media, click a dialog, or perform other interaction beyond the attacker's read/open.\nS:U - The slab out-of-bounds read and any resulting kernel memory misuse stay within the host kernel security domain; no VM escape, IOMMU bypass, or sandbox boundary is crossed.\nC:H - get_unaligned_le32 reads up to four bytes past the kmalloc buffer holding the inline extent, leaking adjacent slab contents that can include kernel pointers and enable further kernel memory disclosure.\nI:H - Slab-out-of-bounds access is kernel memory corruption; adjacent kmalloc objects can be groomed and the disclosed pointers chained into arbitrary write or control-flow hijack primitives during repeated reads.\nA:H - KASAN reports slab-out-of-bounds in lzo_decompress on read; the invalid access can fault into adjacent slab objects and oops the kernel, and repeated reads can destabilize or hang the host."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/lzo.c"],"versions":[{"version":"a6fa6fae40ec336c7df6155255ae64ebef43a8bc","lessThan":"fc50b475ad27f50b4dcc98fc4c44e8802bc1b248","status":"affected","versionType":"git"},{"version":"a6fa6fae40ec336c7df6155255ae64ebef43a8bc","lessThan":"0fa78ef637deb5dbe341582f88553a4bce496de0","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/lzo.c"],"versions":[{"version":"2.6.38","status":"affected"},{"version":"0","lessThan":"2.6.38","status":"unaffected","versionType":"semver"},{"version":"7.1.9","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.38","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/fc50b475ad27f50b4dcc98fc4c44e8802bc1b248"},{"url":"https://git.kernel.org/stable/c/0fa78ef637deb5dbe341582f88553a4bce496de0"}],"title":"btrfs: lzo: reject inline extents without valid headers","x_generator":{"engine":"bippy-1.2.0"}}}}