# CVE-2025-40290: xsk: avoid data corruption on cq descriptor number

> A NULL pointer dereference in the Linux kernel's XSK subsystem causes a kernel panic, leading to denial of service.

- **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-2025-40290, DEBIAN-CVE-2025-40290, GHSA-gjg9-4x43-9rhh, UBUNTU-CVE-2025-40290

## What is CVE-2025-40290?

CVE-2025-40290 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:

xsk: avoid data corruption on cq descriptor number

Since commit 30f241fcf52a ("xsk: Fix immature cq descriptor
production"), the descriptor number is stored in skb control block and
xsk_cq_submit_addr_locked() relies on it to put the umem addrs onto
pool's completion queue.

skb control block shouldn't be used for this purpose as after transmit
xsk doesn't have control over it and other subsystems could use it. This
leads to the following kernel panic due to a NULL pointer dereference.

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: Oops: 0000 [#1] SMP NOPTI
 CPU: 2 UID: 1 PID: 927 Comm: p4xsk.bin Not tainted 6.16.12+deb14-cloud-amd64 #1 PREEMPT(lazy)  Debian 6.16.12-1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
 RIP: 0010:xsk_destruct_skb+0xd0/0x180
 [...]
 Call Trace:
  <IRQ>
  ? napi_complete_done+0x7a/0x1a0
  ip_rcv_core+0x1bb/0x340
  ip_rcv+0x30/0x1f0
  __netif_receive_skb_one_core+0x85/0xa0
  process_backlog+0x87/0x130
  __napi_poll+0x28/0x180
  net_rx_action+0x339/0x420
  handle_softirqs+0xdc/0x320
  ? handle_edge_irq+0x90/0x1e0
  do_softirq.part.0+0x3b/0x60
  </IRQ>
  <TASK>
  __local_bh_enable_ip+0x60/0x70
  __dev_direct_xmit+0x14e/0x1f0
  __xsk_generic_xmit+0x482/0xb70
  ? __remove_hrtimer+0x41/0xa0
  ? __xsk_generic_xmit+0x51/0xb70
  ? _raw_spin_unlock_irqrestore+0xe/0x40
  xsk_sendmsg+0xda/0x1c0
  __sys_sendto+0x1ee/0x200
  __x64_sys_sendto+0x24/0x30
  do_syscall_64+0x84/0x2f0
  ? __pfx_pollwake+0x10/0x10
  ? __rseq_handle_notify_resume+0xad/0x4c0
  ? restore_fpregs_from_fpstate+0x3c/0x90
  ? switch_fpu_return+0x5b/0xe0
  ? do_syscall_64+0x204/0x2f0
  ? do_syscall_64+0x204/0x2f0
  ? do_syscall_64+0x204/0x2f0
  entry_SYSCALL_64_after_hwframe+0x76/0x7e
  </TASK>
 [...]
 Kernel panic - not syncing: Fatal exception in interrupt
 Kernel Offset: 0x1c000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)

Instead use the skb destructor_arg pointer along with pointer tagging.
As pointers are always aligned to 8B, use the bottom bit to indicate
whether this a single address or an allocated struct containing several
addresses.

## Which versions are affected by CVE-2025-40290?


## How do I fix CVE-2025-40290?

Apply the vendor's patch.

## Is CVE-2025-40290 being exploited?

There is no known exploitation of CVE-2025-40290 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40290 and fix it if it is affected.

What it is: CVE-2025-40290 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-2025-40290 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-2025-40290/ (Markdown: https://insights.sbomify.com/CVE-2025-40290/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40290
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40290
- OSV: https://osv.dev/vulnerability/CVE-2025-40290

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40290/
Summaries are generated and may contain mistakes; the official description above is the record.