# 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.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** Yes
- **Published:** 8 May 2026
- **Updated:** 14 Jun 2026
- **Also known as:** BELL-CVE-2026-43349, DEBIAN-CVE-2026-43349, GHSA-9fq9-rx75-mm5g, UBUNTU-CVE-2026-43349

## 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 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2026-43349?

It affects 1 product.


Products: 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43349 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-43349 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43349/ (Markdown: https://insights.sbomify.com/CVE-2026-43349/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43349
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43349
- OSV: https://osv.dev/vulnerability/CVE-2026-43349

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43349/
Summaries are generated and may contain mistakes; the official description above is the record.