CVE-2026-43349 f2fs: fix to avoid uninit-value access in f2fs_sanity_check_node_footer
An attacker with mount privileges can trigger an uninitialized memory access in the f2fs filesystem, potentially leaking kernel memory or causing a system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43349?
CVE-2026-43349 is a medium-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid uninit-value access in f2fs_sanity_check_node_footer
syzbot reported a f2fs bug as below:
BUG: KMSAN: uninit-value in f2fs_sanity_check_node_footer+0x374/0xa20 fs/f2fs/node.c:1520 f2fs_sanity_check_node_footer+0x374/0xa20 fs/f2fs/node.c:1520 f2fs_finish_read_bio+0xe1e/0x1d60 fs/f2fs/data.c:177 f2fs_read_end_io+0x6ab/0x2220 fs/f2fs/data.c:-1 bio_endio+0x1006/0x1160 block/bio.c:1792 submit_bio_noacct+0x533/0x2960 block/blk-core.c:891 submit_bio+0x57a/0x620 block/blk-core.c:926 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] f2fs_submit_read_bio+0x12c/0x360 fs/f2fs/data.c:557 f2fs_submit_page_bio+0xee2/0x1450 fs/f2fs/data.c:775 read_node_folio+0x384/0x4b0 fs/f2fs/node.c:1481 __get_node_folio+0x5db/0x15d0 fs/f2fs/node.c:1576 f2fs_get_inode_folio+0x40/0x50 fs/f2fs/node.c:1623 do_read_inode fs/f2fs/inode.c:425 [inline] f2fs_iget+0x1209/0x9380 fs/f2fs/inode.c:596 f2fs_fill_super+0x8f5a/0xb2e0 fs/f2fs/super.c:5184 get_tree_bdev_flags+0x6e6/0x920 fs/super.c:1694 get_tree_bdev+0x38/0x50 fs/super.c:1717 f2fs_get_tree+0x35/0x40 fs/f2fs/super.c:5436 vfs_get_tree+0xb3/0x5d0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3763 [inline] do_new_mount+0x885/0x1dd0 fs/namespace.c:3839 path_mount+0x7a2/0x20b0 fs/namespace.c:4159 do_mount fs/namespace.c:4172 [inline] __do_sys_mount fs/namespace.c:4361 [inline] __se_sys_mount+0x704/0x7f0 fs/namespace.c:4338 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4338 x64_sys_call+0x39f0/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
The root cause is: in f2fs_finish_read_bio(), we may access uninit data in folio if we failed to read the data from device into folio, let's add a check condition to avoid such issue.
Weakness: CWE-908
Which versions are affected by CVE-2026-43349?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43349?
Apply the vendor's patch.
Is CVE-2026-43349 being exploited?
There is no known exploitation of CVE-2026-43349 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43349, DEBIAN-CVE-2026-43349, GHSA-9fq9-rx75-mm5g, UBUNTU-CVE-2026-43349.