# CVE-2023-53763: Revert "f2fs: fix to do sanity check on extent cache correctly"

> A logic error in the f2fs filesystem's extent cache handling causes an out-of-bounds array index, leading to a kernel crash during mount.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 Dec 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-53763, DEBIAN-CVE-2023-53763, GHSA-5fw5-8689-q6mq, UBUNTU-CVE-2023-53763

## What is CVE-2023-53763?

CVE-2023-53763 is a high-severity vulnerability in Linux, published on 8 Dec 2025. 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:

Revert "f2fs: fix to do sanity check on extent cache correctly"

syzbot reports a f2fs bug as below:

UBSAN: array-index-out-of-bounds in fs/f2fs/f2fs.h:3275:19
index 1409 is out of range for type '__le32[923]' (aka 'unsigned int[923]')
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:217 [inline]
 __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348
 inline_data_addr fs/f2fs/f2fs.h:3275 [inline]
 __recover_inline_status fs/f2fs/inode.c:113 [inline]
 do_read_inode fs/f2fs/inode.c:480 [inline]
 f2fs_iget+0x4730/0x48b0 fs/f2fs/inode.c:604
 f2fs_fill_super+0x640e/0x80c0 fs/f2fs/super.c:4601
 mount_bdev+0x276/0x3b0 fs/super.c:1391
 legacy_get_tree+0xef/0x190 fs/fs_context.c:611
 vfs_get_tree+0x8c/0x270 fs/super.c:1519
 do_new_mount+0x28f/0xae0 fs/namespace.c:3335
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The issue was bisected to:

commit d48a7b3a72f121655d95b5157c32c7d555e44c05
Author: Chao Yu <chao@kernel.org>
Date:   Mon Jan 9 03:49:20 2023 +0000

    f2fs: fix to do sanity check on extent cache correctly

The root cause is we applied both v1 and v2 of the patch, v2 is the right
fix, so it needs to revert v1 in order to fix reported issue.

v1:
commit d48a7b3a72f1 ("f2fs: fix to do sanity check on extent cache correctly")
https://lore.kernel.org/lkml/20230109034920.492914-1-chao@kernel.org/

v2:
commit 269d11948100 ("f2fs: fix to do sanity check on extent cache correctly")
https://lore.kernel.org/lkml/20230207134808.1827869-1-chao@kernel.org/

## Which versions are affected by CVE-2023-53763?


## How do I fix CVE-2023-53763?

Apply the vendor's patch.

## Is CVE-2023-53763 being exploited?

There is no known exploitation of CVE-2023-53763 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53763 and fix it if it is affected.

What it is: CVE-2023-53763 is a high-severity vulnerability in Linux, published on 8 Dec 2025. 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-2023-53763 in the wild and no public exploit code.

Affected product: Linux. 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-2023-53763/ (Markdown: https://insights.sbomify.com/CVE-2023-53763/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53763
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53763
- OSV: https://osv.dev/vulnerability/CVE-2023-53763

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53763/
Summaries are generated and may contain mistakes; the official description above is the record.