# CVE-2026-31505: iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

> A race condition in the iavf driver allows out-of-bounds writes when changing channels and reading stats simultaneously, potentially leading to code execution or crashes.

- **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:** 22 Apr 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-83246, BELL-CVE-2026-31505, DEBIAN-CVE-2026-31505, GHSA-j72v-jx24-rm3p, ROOT-OS-DEBIAN-12-CVE-2026-31505, ROOT-OS-DEBIAN-13-CVE-2026-31505, ROOT-OS-UBUNTU-2404-CVE-2026-31505, UBUNTU-CVE-2026-31505

## What is CVE-2026-31505?

CVE-2026-31505 is a high-severity vulnerability in Linux kernel, published on 22 Apr 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:

iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

iavf incorrectly uses real_num_tx_queues for ETH_SS_STATS. Since the
value could change in runtime, we should use num_tx_queues instead.

Moreover iavf_get_ethtool_stats() uses num_active_queues while
iavf_get_sset_count() and iavf_get_stat_strings() use
real_num_tx_queues, which triggers out-of-bounds writes when we do
"ethtool -L" and "ethtool -S" simultaneously [1].

For example when we change channels from 1 to 8, Thread 3 could be
scheduled before Thread 2, and out-of-bounds writes could be triggered
in Thread 3:

Thread 1 (ethtool -L)       Thread 2 (work)        Thread 3 (ethtool -S)
iavf_set_channels()
...
iavf_alloc_queues()
-> num_active_queues = 8
iavf_schedule_finish_config()
                                                   iavf_get_sset_count()
                                                   real_num_tx_queues: 1
                                                   -> buffer for 1 queue
                                                   iavf_get_ethtool_stats()
                                                   num_active_queues: 8
                                                   -> out-of-bounds!
                            iavf_finish_config()
                            -> real_num_tx_queues = 8

Use immutable num_tx_queues in all related functions to avoid the issue.

[1]
 BUG: KASAN: vmalloc-out-of-bounds in iavf_add_one_ethtool_stat+0x200/0x270
 Write of size 8 at addr ffffc900031c9080 by task ethtool/5800

 CPU: 1 UID: 0 PID: 5800 Comm: ethtool Not tainted 6.19.0-enjuk-08403-g8137e3db7f1c #241 PREEMPT(full)
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 Call Trace:
  <TASK>
  dump_stack_lvl+0x6f/0xb0
  print_report+0x170/0x4f3
  kasan_report+0xe1/0x180
  iavf_add_one_ethtool_stat+0x200/0x270
  iavf_get_ethtool_stats+0x14c/0x2e0
  __dev_ethtool+0x3d0c/0x5830
  dev_ethtool+0x12d/0x270
  dev_ioctl+0x53c/0xe30
  sock_do_ioctl+0x1a9/0x270
  sock_ioctl+0x3d4/0x5e0
  __x64_sys_ioctl+0x137/0x1c0
  do_syscall_64+0xf3/0x690
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
 RIP: 0033:0x7f7da0e6e36d
 ...
  </TASK>

 The buggy address belongs to a 1-page vmalloc region starting at 0xffffc900031c9000 allocated at __dev_ethtool+0x3cc9/0x5830
 The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000
 index:0xffff88813a013de0 pfn:0x13a013
 flags: 0x200000000000000(node=0|zone=2)
 raw: 0200000000000000 0000000000000000 dead000000000122 0000000000000000
 raw: ffff88813a013de0 0000000000000000 00000001ffffffff 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  ffffc900031c8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
  ffffc900031c9000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 >ffffc900031c9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                    ^
  ffffc900031c9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
  ffffc900031c9180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-31505?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31505?

Apply the vendor's patch.

## Is CVE-2026-31505 being exploited?

There is no known exploitation of CVE-2026-31505 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-2026-31505 and fix it if it is affected.

What it is: CVE-2026-31505 is a high-severity vulnerability in Linux kernel, published on 22 Apr 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-2026-31505 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-2026-31505/ (Markdown: https://insights.sbomify.com/CVE-2026-31505/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31505
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31505
- OSV: https://osv.dev/vulnerability/CVE-2026-31505

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31505/
Summaries are generated and may contain mistakes; the official description above is the record.