# CVE-2026-45970: bonding: alb: fix UAF in rlb_arp_recv during bond up/down

> A use-after-free in the Linux kernel bonding driver during bond up/down cycles can cause a system crash.

- **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:** 27 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-45970, DEBIAN-CVE-2026-45970, GHSA-mc9g-h8jv-5cp3, ROOT-OS-DEBIAN-11-CVE-2026-45970, ROOT-OS-UBUNTU-2204-CVE-2026-45970, ROOT-OS-UBUNTU-2404-CVE-2026-45970, UBUNTU-CVE-2026-45970

## What is CVE-2026-45970?

CVE-2026-45970 is a high-severity use after free vulnerability in Linux kernel, published on 27 May 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:

bonding: alb: fix UAF in rlb_arp_recv during bond up/down

The ALB RX path may access rx_hashtbl concurrently with bond
teardown. During rapid bond up/down cycles, rlb_deinitialize()
frees rx_hashtbl while RX handlers are still running, leading
to a null pointer dereference detected by KASAN.

However, the root cause is that rlb_arp_recv() can still be accessed
after setting recv_probe to NULL, which is actually a use-after-free
(UAF) issue. That is the reason for using the referenced commit in the
Fixes tag.

[  214.174138] Oops: general protection fault, probably for non-canonical address 0xdffffc000000001d: 0000 [#1] SMP KASAN PTI
[  214.186478] KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]
[  214.194933] CPU: 30 UID: 0 PID: 2375 Comm: ping Kdump: loaded Not tainted 6.19.0-rc8+ #2 PREEMPT(voluntary)
[  214.205907] Hardware name: Dell Inc. PowerEdge R730/0WCJNT, BIOS 2.14.0 01/14/2022
[  214.214357] RIP: 0010:rlb_arp_recv+0x505/0xab0 [bonding]
[  214.220320] Code: 0f 85 2b 05 00 00 48 b8 00 00 00 00 00 fc ff df 40 0f b6 ed 48 c1 e5 06 49 03 ad 78 01 00 00 48 8d 7d 28 48 89 fa 48 c1 ea 03 <0f> b6
 04 02 84 c0 74 06 0f 8e 12 05 00 00 80 7d 28 00 0f 84 8c 00
[  214.241280] RSP: 0018:ffffc900073d8870 EFLAGS: 00010206
[  214.247116] RAX: dffffc0000000000 RBX: ffff888168556822 RCX: ffff88816855681e
[  214.255082] RDX: 000000000000001d RSI: dffffc0000000000 RDI: 00000000000000e8
[  214.263048] RBP: 00000000000000c0 R08: 0000000000000002 R09: ffffed11192021c8
[  214.271013] R10: ffff8888c9010e43 R11: 0000000000000001 R12: 1ffff92000e7b119
[  214.278978] R13: ffff8888c9010e00 R14: ffff888168556822 R15: ffff888168556810
[  214.286943] FS:  00007f85d2d9cb80(0000) GS:ffff88886ccb3000(0000) knlGS:0000000000000000
[  214.295966] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  214.302380] CR2: 00007f0d047b5e34 CR3: 00000008a1c2e002 CR4: 00000000001726f0
[  214.310347] Call Trace:
[  214.313070]  <IRQ>
[  214.315318]  ? __pfx_rlb_arp_recv+0x10/0x10 [bonding]
[  214.320975]  bond_handle_frame+0x166/0xb60 [bonding]
[  214.326537]  ? __pfx_bond_handle_frame+0x10/0x10 [bonding]
[  214.332680]  __netif_receive_skb_core.constprop.0+0x576/0x2710
[  214.339199]  ? __pfx_arp_process+0x10/0x10
[  214.343775]  ? sched_balance_find_src_group+0x98/0x630
[  214.349513]  ? __pfx___netif_receive_skb_core.constprop.0+0x10/0x10
[  214.356513]  ? arp_rcv+0x307/0x690
[  214.360311]  ? __pfx_arp_rcv+0x10/0x10
[  214.364499]  ? __lock_acquire+0x58c/0xbd0
[  214.368975]  __netif_receive_skb_one_core+0xae/0x1b0
[  214.374518]  ? __pfx___netif_receive_skb_one_core+0x10/0x10
[  214.380743]  ? lock_acquire+0x10b/0x140
[  214.385026]  process_backlog+0x3f1/0x13a0
[  214.389502]  ? process_backlog+0x3aa/0x13a0
[  214.394174]  __napi_poll.constprop.0+0x9f/0x370
[  214.399233]  net_rx_action+0x8c1/0xe60
[  214.403423]  ? __pfx_net_rx_action+0x10/0x10
[  214.408193]  ? lock_acquire.part.0+0xbd/0x260
[  214.413058]  ? sched_clock_cpu+0x6c/0x540
[  214.417540]  ? mark_held_locks+0x40/0x70
[  214.421920]  handle_softirqs+0x1fd/0x860
[  214.426302]  ? __pfx_handle_softirqs+0x10/0x10
[  214.431264]  ? __neigh_event_send+0x2d6/0xf50
[  214.436131]  do_softirq+0xb1/0xf0
[  214.439830]  </IRQ>

The issue is reproducible by repeatedly running
ip link set bond0 up/down while receiving ARP messages, where
rlb_arp_recv() can race with rlb_deinitialize() and dereference
a freed rx_hashtbl entry.

Fix this by setting recv_probe to NULL and then calling
synchronize_net() to wait for any concurrent RX processing to finish.
This ensures that no RX handler can access rx_hashtbl after it is freed
in bond_alb_deinitialize().

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-45970?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-45970?

Apply the vendor's patch.

## Is CVE-2026-45970 being exploited?

There is no known exploitation of CVE-2026-45970 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-2026-45970 and fix it if it is affected.

What it is: CVE-2026-45970 is a high-severity use after free vulnerability in Linux kernel, published on 27 May 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-2026-45970 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-2026-45970/ (Markdown: https://insights.sbomify.com/CVE-2026-45970/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45970
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45970
- OSV: https://osv.dev/vulnerability/CVE-2026-45970

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45970/
Summaries are generated and may contain mistakes; the official description above is the record.