# CVE-2026-23212: bonding: annotate data-races around slave->last_rx

> A data race in the Linux kernel bonding driver can lead to inconsistent state, potentially causing instability or unexpected behavior.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/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:** 18 Feb 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-77865, BELL-CVE-2026-23212, DEBIAN-CVE-2026-23212, GHSA-phqg-p332-q7vc, ROOT-OS-DEBIAN-11-CVE-2026-23212, ROOT-OS-UBUNTU-2204-CVE-2026-23212, ROOT-OS-UBUNTU-2404-CVE-2026-23212, UBUNTU-CVE-2026-23212

## What is CVE-2026-23212?

CVE-2026-23212 is a medium-severity vulnerability in Linux kernel, published on 18 Feb 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: annotate data-races around slave->last_rx

slave->last_rx and slave->target_last_arp_rx[...] can be read and written
locklessly. Add READ_ONCE() and WRITE_ONCE() annotations.

syzbot reported:

BUG: KCSAN: data-race in bond_rcv_validate / bond_rcv_validate

write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 1:
  bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335
  bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533
  __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039
  __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
  __netif_receive_skb+0x59/0x270 net/core/dev.c:6265
  netif_receive_skb_internal net/core/dev.c:6351 [inline]
  netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410
...

write to 0xffff888149f0d428 of 8 bytes by interrupt on cpu 0:
  bond_rcv_validate+0x202/0x7a0 drivers/net/bonding/bond_main.c:3335
  bond_handle_frame+0xde/0x5e0 drivers/net/bonding/bond_main.c:1533
  __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6039
  __netif_receive_skb_one_core net/core/dev.c:6150 [inline]
  __netif_receive_skb+0x59/0x270 net/core/dev.c:6265
  netif_receive_skb_internal net/core/dev.c:6351 [inline]
  netif_receive_skb+0x4b/0x2d0 net/core/dev.c:6410
  br_netif_receive_skb net/bridge/br_input.c:30 [inline]
  NF_HOOK include/linux/netfilter.h:318 [inline]
...

value changed: 0x0000000100005365 -> 0x0000000100005366

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-23212?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23212?

Apply the vendor's patch.

## Is CVE-2026-23212 being exploited?

There is no known exploitation of CVE-2026-23212 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-2026-23212 and fix it if it is affected.

What it is: CVE-2026-23212 is a medium-severity vulnerability in Linux kernel, published on 18 Feb 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-2026-23212 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-2026-23212/ (Markdown: https://insights.sbomify.com/CVE-2026-23212/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23212
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23212
- OSV: https://osv.dev/vulnerability/CVE-2026-23212

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23212/
Summaries are generated and may contain mistakes; the official description above is the record.