# CVE-2023-53538: btrfs: insert tree mod log move in push_node_left

> A race condition in the Btrfs file system can cause a kernel panic, leading to a 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:** 4 Oct 2025
- **Updated:** 3 Oct 2026
- **Also known as:** AZL-77393, BELL-CVE-2023-53538, DEBIAN-CVE-2023-53538, GHSA-42hw-46gp-ffq7, ROOT-OS-DEBIAN-11-CVE-2023-53538, ROOT-OS-DEBIAN-12-CVE-2023-53538, ROOT-OS-UBUNTU-2204-CVE-2023-53538, UBUNTU-CVE-2023-53538

## What is CVE-2023-53538?

CVE-2023-53538 is a medium-severity vulnerability in Linux kernel, published on 4 Oct 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:

btrfs: insert tree mod log move in push_node_left

There is a fairly unlikely race condition in tree mod log rewind that
can result in a kernel panic which has the following trace:

  [530.569] BTRFS critical (device sda3): unable to find logical 0 length 4096
  [530.585] BTRFS critical (device sda3): unable to find logical 0 length 4096
  [530.602] BUG: kernel NULL pointer dereference, address: 0000000000000002
  [530.618] #PF: supervisor read access in kernel mode
  [530.629] #PF: error_code(0x0000) - not-present page
  [530.641] PGD 0 P4D 0
  [530.647] Oops: 0000 [#1] SMP
  [530.654] CPU: 30 PID: 398973 Comm: below Kdump: loaded Tainted: G S         O  K   5.12.0-0_fbk13_clang_7455_gb24de3bdb045 #1
  [530.680] Hardware name: Quanta Mono Lake-M.2 SATA 1HY9U9Z001G/Mono Lake-M.2 SATA, BIOS F20_3A15 08/16/2017
  [530.703] RIP: 0010:__btrfs_map_block+0xaa/0xd00
  [530.755] RSP: 0018:ffffc9002c2f7600 EFLAGS: 00010246
  [530.767] RAX: ffffffffffffffea RBX: ffff888292e41000 RCX: f2702d8b8be15100
  [530.784] RDX: ffff88885fda6fb8 RSI: ffff88885fd973c8 RDI: ffff88885fd973c8
  [530.800] RBP: ffff888292e410d0 R08: ffffffff82fd7fd0 R09: 00000000fffeffff
  [530.816] R10: ffffffff82e57fd0 R11: ffffffff82e57d70 R12: 0000000000000000
  [530.832] R13: 0000000000001000 R14: 0000000000001000 R15: ffffc9002c2f76f0
  [530.848] FS:  00007f38d64af000(0000) GS:ffff88885fd80000(0000) knlGS:0000000000000000
  [530.866] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [530.880] CR2: 0000000000000002 CR3: 00000002b6770004 CR4: 00000000003706e0
  [530.896] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [530.912] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [530.928] Call Trace:
  [530.934]  ? btrfs_printk+0x13b/0x18c
  [530.943]  ? btrfs_bio_counter_inc_blocked+0x3d/0x130
  [530.955]  btrfs_map_bio+0x75/0x330
  [530.963]  ? kmem_cache_alloc+0x12a/0x2d0
  [530.973]  ? btrfs_submit_metadata_bio+0x63/0x100
  [530.984]  btrfs_submit_metadata_bio+0xa4/0x100
  [530.995]  submit_extent_page+0x30f/0x360
  [531.004]  read_extent_buffer_pages+0x49e/0x6d0
  [531.015]  ? submit_extent_page+0x360/0x360
  [531.025]  btree_read_extent_buffer_pages+0x5f/0x150
  [531.037]  read_tree_block+0x37/0x60
  [531.046]  read_block_for_search+0x18b/0x410
  [531.056]  btrfs_search_old_slot+0x198/0x2f0
  [531.066]  resolve_indirect_ref+0xfe/0x6f0
  [531.076]  ? ulist_alloc+0x31/0x60
  [531.084]  ? kmem_cache_alloc_trace+0x12e/0x2b0
  [531.095]  find_parent_nodes+0x720/0x1830
  [531.105]  ? ulist_alloc+0x10/0x60
  [531.113]  iterate_extent_inodes+0xea/0x370
  [531.123]  ? btrfs_previous_extent_item+0x8f/0x110
  [531.134]  ? btrfs_search_path_in_tree+0x240/0x240
  [531.146]  iterate_inodes_from_logical+0x98/0xd0
  [531.157]  ? btrfs_search_path_in_tree+0x240/0x240
  [531.168]  btrfs_ioctl_logical_to_ino+0xd9/0x180
  [531.179]  btrfs_ioctl+0xe2/0x2eb0

This occurs when logical inode resolution takes a tree mod log sequence
number, and then while backref walking hits a rewind on a busy node
which has the following sequence of tree mod log operations (numbers
filled in from a specific example, but they are somewhat arbitrary)

  REMOVE_WHILE_FREEING slot 532
  REMOVE_WHILE_FREEING slot 531
  REMOVE_WHILE_FREEING slot 530
  ...
  REMOVE_WHILE_FREEING slot 0
  REMOVE slot 455
  REMOVE slot 454
  REMOVE slot 453
  ...
  REMOVE slot 0
  ADD slot 455
  ADD slot 454
  ADD slot 453
  ...
  ADD slot 0
  MOVE src slot 0 -> dst slot 456 nritems 533
  REMOVE slot 455
  REMOVE slot 454
  REMOVE slot 453
  ...
  REMOVE slot 0

When this sequence gets applied via btrfs_tree_mod_log_rewind, it
allocates a fresh rewind eb, and first inserts the correct key info for
the 533 elements, then overwrites the first 456 of them, then decrements
the count by 456 via the add ops, then rewinds the move by doing a
memmove from 456:988->0:532. We have never written anything past 532,
---truncated---

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2023-53538?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53538?

Apply the vendor's patch.

## Is CVE-2023-53538 being exploited?

There is no known exploitation of CVE-2023-53538 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-2023-53538 and fix it if it is affected.

What it is: CVE-2023-53538 is a medium-severity vulnerability in Linux kernel, published on 4 Oct 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-2023-53538 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-2023-53538/ (Markdown: https://insights.sbomify.com/CVE-2023-53538/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53538
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53538
- OSV: https://osv.dev/vulnerability/CVE-2023-53538

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53538/
Summaries are generated and may contain mistakes; the official description above is the record.