# CVE-2025-21752: btrfs: don't use btrfs_set_item_key_safe on RAID stripe-extents

> A flaw in the Linux kernel's btrfs filesystem can cause a kernel panic and system crash when modifying RAID stripe-extents.

- **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:** 27 Feb 2025
- **Updated:** 23 May 2026
- **Also known as:** AZL-87126, BELL-CVE-2025-21752, DEBIAN-CVE-2025-21752, GHSA-r9cf-94mr-8v6q, ROOT-OS-DEBIAN-13-CVE-2025-21752, ROOT-OS-UBUNTU-2204-CVE-2025-21752, ROOT-OS-UBUNTU-2404-CVE-2025-21752, UBUNTU-CVE-2025-21752

## What is CVE-2025-21752?

CVE-2025-21752 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 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: don't use btrfs_set_item_key_safe on RAID stripe-extents

Don't use btrfs_set_item_key_safe() to modify the keys in the RAID
stripe-tree, as this can lead to corruption of the tree, which is caught
by the checks in btrfs_set_item_key_safe():

 BTRFS info (device nvme1n1): leaf 49168384 gen 15 total ptrs 194 free space 8329 owner 12
 BTRFS info (device nvme1n1): refs 2 lock_owner 1030 current 1030
  [ snip ]
  item 105 key (354549760 230 20480) itemoff 14587 itemsize 16
                  stride 0 devid 5 physical 67502080
  item 106 key (354631680 230 4096) itemoff 14571 itemsize 16
                  stride 0 devid 1 physical 88559616
  item 107 key (354631680 230 32768) itemoff 14555 itemsize 16
                  stride 0 devid 1 physical 88555520
  item 108 key (354717696 230 28672) itemoff 14539 itemsize 16
                  stride 0 devid 2 physical 67604480
  [ snip ]
 BTRFS critical (device nvme1n1): slot 106 key (354631680 230 32768) new key (354635776 230 4096)
 ------------[ cut here ]------------
 kernel BUG at fs/btrfs/ctree.c:2602!
 Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
 CPU: 1 UID: 0 PID: 1055 Comm: fsstress Not tainted 6.13.0-rc1+ #1464
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
 RIP: 0010:btrfs_set_item_key_safe+0xf7/0x270
 Code: <snip>
 RSP: 0018:ffffc90001337ab0 EFLAGS: 00010287
 RAX: 0000000000000000 RBX: ffff8881115fd000 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000000001 RDI: 00000000ffffffff
 RBP: ffff888110ed6f50 R08: 00000000ffffefff R09: ffffffff8244c500
 R10: 00000000ffffefff R11: 00000000ffffffff R12: ffff888100586000
 R13: 00000000000000c9 R14: ffffc90001337b1f R15: ffff888110f23b58
 FS:  00007f7d75c72740(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fa811652c60 CR3: 0000000111398001 CR4: 0000000000370eb0
 Call Trace:
  <TASK>
  ? __die_body.cold+0x14/0x1a
  ? die+0x2e/0x50
  ? do_trap+0xca/0x110
  ? do_error_trap+0x65/0x80
  ? btrfs_set_item_key_safe+0xf7/0x270
  ? exc_invalid_op+0x50/0x70
  ? btrfs_set_item_key_safe+0xf7/0x270
  ? asm_exc_invalid_op+0x1a/0x20
  ? btrfs_set_item_key_safe+0xf7/0x270
  btrfs_partially_delete_raid_extent+0xc4/0xe0
  btrfs_delete_raid_extent+0x227/0x240
  __btrfs_free_extent.isra.0+0x57f/0x9c0
  ? exc_coproc_segment_overrun+0x40/0x40
  __btrfs_run_delayed_refs+0x2fa/0xe80
  btrfs_run_delayed_refs+0x81/0xe0
  btrfs_commit_transaction+0x2dd/0xbe0
  ? preempt_count_add+0x52/0xb0
  btrfs_sync_file+0x375/0x4c0
  do_fsync+0x39/0x70
  __x64_sys_fsync+0x13/0x20
  do_syscall_64+0x54/0x110
  entry_SYSCALL_64_after_hwframe+0x76/0x7e
 RIP: 0033:0x7f7d7550ef90
 Code: <snip>
 RSP: 002b:00007ffd70237248 EFLAGS: 00000202 ORIG_RAX: 000000000000004a
 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f7d7550ef90
 RDX: 000000000000013a RSI: 000000000040eb28 RDI: 0000000000000004
 RBP: 000000000000001b R08: 0000000000000078 R09: 00007ffd7023725c
 R10: 00007f7d75400390 R11: 0000000000000202 R12: 028f5c28f5c28f5c
 R13: 8f5c28f5c28f5c29 R14: 000000000040b520 R15: 00007f7d75c726c8
  </TASK>

While the root cause of the tree order corruption isn't clear, using
btrfs_duplicate_item() to copy the item and then adjusting both the key
and the per-device physical addresses is a safe way to counter this
problem.

## Which versions are affected by CVE-2025-21752?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-21752?

Apply the vendor's patch.

## Is CVE-2025-21752 being exploited?

There is no known exploitation of CVE-2025-21752 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-2025-21752 and fix it if it is affected.

What it is: CVE-2025-21752 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 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-2025-21752 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-2025-21752/ (Markdown: https://insights.sbomify.com/CVE-2025-21752/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21752
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21752
- OSV: https://osv.dev/vulnerability/CVE-2025-21752

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-21752/
Summaries are generated and may contain mistakes; the official description above is the record.