# CVE-2026-53018: f2fs: avoid reading already updated pages during GC

> A logic error in the f2fs garbage collection process can trigger a kernel bug, leading to a system crash and denial of service.

- **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:** 24 Jun 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-53018, DEBIAN-CVE-2026-53018, GHSA-xw4w-5xc6-fwjx, ROOT-OS-DEBIAN-11-CVE-2026-53018, ROOT-OS-DEBIAN-12-CVE-2026-53018, ROOT-OS-DEBIAN-13-CVE-2026-53018, ROOT-OS-UBUNTU-2204-CVE-2026-53018, ROOT-OS-UBUNTU-2404-CVE-2026-53018, UBUNTU-CVE-2026-53018

## What is CVE-2026-53018?

CVE-2026-53018 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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: avoid reading already updated pages during GC

We found the following issue during fuzz testing:

page: refcount:3 mapcount:0 mapping:00000000b6e89c65 index:0x18b2dc pfn:0x161ba9
memcg:f8ffff800e269c00
aops:f2fs_meta_aops ino:2
flags: 0x52880000000080a9(locked|waiters|uptodate|lru|private|zone=1|kasantag=0x4a)
raw: 52880000000080a9 fffffffec6e17588 fffffffec0ccc088 a7ffff8067063618
raw: 000000000018b2dc 0000000000000009 00000003ffffffff f8ffff800e269c00
page dumped because: VM_BUG_ON_FOLIO(folio_test_uptodate(folio))
page_owner tracks the page as allocated
 post_alloc_hook+0x58c/0x5ec
 prep_new_page+0x34/0x284
 get_page_from_freelist+0x2dcc/0x2e8c
 __alloc_pages_noprof+0x280/0x76c
 __folio_alloc_noprof+0x18/0xac
 __filemap_get_folio+0x6bc/0xdc4
 pagecache_get_page+0x3c/0x104
 do_garbage_collect+0x5c78/0x77a4
 f2fs_gc+0xd74/0x25f0
 gc_thread_func+0xb28/0x2930
 kthread+0x464/0x5d8
 ret_from_fork+0x10/0x20
------------[ cut here ]------------
kernel BUG at mm/filemap.c:1563!
 folio_end_read+0x140/0x168
 f2fs_finish_read_bio+0x5c4/0xb80
 f2fs_read_end_io+0x64c/0x708
 bio_endio+0x85c/0x8c0
 blk_update_request+0x690/0x127c
 scsi_end_request+0x9c/0xb8c
 scsi_io_completion+0xf0/0x250
 scsi_finish_command+0x430/0x45c
 scsi_complete+0x178/0x6d4
 blk_mq_complete_request+0xcc/0x104
 scsi_done_internal+0x214/0x454
 scsi_done+0x24/0x34

which is similar to the problem reported by syzbot:
https://syzkaller.appspot.com/bug?extid=3686758660f980b402dc

This case is consistent with the description in commit 9bf1a3f
("f2fs: avoid GC causing encrypted file corrupted"):
Page 1 is moved from blkaddr A to blkaddr B by move_data_block, and after
being written it is marked as uptodate. Then, Page 1 is moved from blkaddr
B to blkaddr C, VM_BUG_ON_FOLIO was triggered in the endio initiated by
ra_data_block.

There is no need to read Page 1 again from blkaddr B, since it has already
been updated. Therefore, avoid initiating I/O in this case.

## Which versions are affected by CVE-2026-53018?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53018?

Apply the vendor's patch.

## Is CVE-2026-53018 being exploited?

There is no known exploitation of CVE-2026-53018 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-2026-53018 and fix it if it is affected.

What it is: CVE-2026-53018 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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-2026-53018 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-2026-53018/ (Markdown: https://insights.sbomify.com/CVE-2026-53018/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53018
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53018
- OSV: https://osv.dev/vulnerability/CVE-2026-53018

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53018/
Summaries are generated and may contain mistakes; the official description above is the record.