# CVE-2025-71087: iavf: fix off-by-one issues in iavf_config_rss_reg()

> An off-by-one error in the iavf network driver allows out-of-bounds memory reads and writes, potentially causing system crashes or information disclosure.

- **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:** 13 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2025-71087, DEBIAN-CVE-2025-71087, GHSA-pwf8-g74p-w24j, ROOT-OS-DEBIAN-11-CVE-2025-71087, ROOT-OS-DEBIAN-12-CVE-2025-71087, ROOT-OS-DEBIAN-13-CVE-2025-71087, ROOT-OS-UBUNTU-2204-CVE-2025-71087, ROOT-OS-UBUNTU-2404-CVE-2025-71087, UBUNTU-CVE-2025-71087

## What is CVE-2025-71087?

CVE-2025-71087 is a medium-severity memory corruption vulnerability in Linux kernel, published on 13 Jan 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 off-by-one issues in iavf_config_rss_reg()

There are off-by-one bugs when configuring RSS hash key and lookup
table, causing out-of-bounds reads to memory [1] and out-of-bounds
writes to device registers.

Before commit 43a3d9ba34c9 ("i40evf: Allow PF driver to configure RSS"),
the loop upper bounds were:
    i <= I40E_VFQF_{HKEY,HLUT}_MAX_INDEX
which is safe since the value is the last valid index.

That commit changed the bounds to:
    i <= adapter->rss_{key,lut}_size / 4
where `rss_{key,lut}_size / 4` is the number of dwords, so the last
valid index is `(rss_{key,lut}_size / 4) - 1`. Therefore, using `<=`
accesses one element past the end.

Fix the issues by using `<` instead of `<=`, ensuring we do not exceed
the bounds.

[1] KASAN splat about rss_key_size off-by-one
  BUG: KASAN: slab-out-of-bounds in iavf_config_rss+0x619/0x800
  Read of size 4 at addr ffff888102c50134 by task kworker/u8:6/63

  CPU: 0 UID: 0 PID: 63 Comm: kworker/u8:6 Not tainted 6.18.0-rc2-enjuk-tnguy-00378-g3005f5b77652-dirty #156 PREEMPT(voluntary)
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
  Workqueue: iavf iavf_watchdog_task
  Call Trace:
   <TASK>
   dump_stack_lvl+0x6f/0xb0
   print_report+0x170/0x4f3
   kasan_report+0xe1/0x1a0
   iavf_config_rss+0x619/0x800
   iavf_watchdog_task+0x2be7/0x3230
   process_one_work+0x7fd/0x1420
   worker_thread+0x4d1/0xd40
   kthread+0x344/0x660
   ret_from_fork+0x249/0x320
   ret_from_fork_asm+0x1a/0x30
   </TASK>

  Allocated by task 63:
   kasan_save_stack+0x30/0x50
   kasan_save_track+0x14/0x30
   __kasan_kmalloc+0x7f/0x90
   __kmalloc_noprof+0x246/0x6f0
   iavf_watchdog_task+0x28fc/0x3230
   process_one_work+0x7fd/0x1420
   worker_thread+0x4d1/0xd40
   kthread+0x344/0x660
   ret_from_fork+0x249/0x320
   ret_from_fork_asm+0x1a/0x30

  The buggy address belongs to the object at ffff888102c50100
   which belongs to the cache kmalloc-64 of size 64
  The buggy address is located 0 bytes to the right of
   allocated 52-byte region [ffff888102c50100, ffff888102c50134)

  The buggy address belongs to the physical page:
  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x102c50
  flags: 0x200000000000000(node=0|zone=2)
  page_type: f5(slab)
  raw: 0200000000000000 ffff8881000418c0 dead000000000122 0000000000000000
  raw: 0000000000000000 0000000080200020 00000000f5000000 0000000000000000
  page dumped because: kasan: bad access detected

  Memory state around the buggy address:
   ffff888102c50000: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
   ffff888102c50080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
  >ffff888102c50100: 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc fc
                                       ^
   ffff888102c50180: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
   ffff888102c50200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Weakness: CWE-193 (Off-by-one Error), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2025-71087?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71087?

Apply the vendor's patch.

## Is CVE-2025-71087 being exploited?

There is no known exploitation of CVE-2025-71087 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-2025-71087 and fix it if it is affected.

What it is: CVE-2025-71087 is a medium-severity memory corruption vulnerability in Linux kernel, published on 13 Jan 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-2025-71087 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-2025-71087/ (Markdown: https://insights.sbomify.com/CVE-2025-71087/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71087
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71087
- OSV: https://osv.dev/vulnerability/CVE-2025-71087

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71087/
Summaries are generated and may contain mistakes; the official description above is the record.