# CVE-2026-43083: net: ioam6: fix OOB and missing lock

> An out-of-bounds access in the Linux kernel IOAM6 module allows attackers to cause denial of service or potentially execute code via crafted network packets.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 May 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-85929, BELL-CVE-2026-43083, DEBIAN-CVE-2026-43083, GHSA-29pf-hv9p-f96v, ROOT-OS-DEBIAN-12-CVE-2026-43083, ROOT-OS-DEBIAN-13-CVE-2026-43083, ROOT-OS-UBUNTU-2404-CVE-2026-43083, UBUNTU-CVE-2026-43083

## What is CVE-2026-43083?

CVE-2026-43083 is a critical memory corruption vulnerability in Linux kernel, published on 6 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: ioam6: fix OOB and missing lock

When trace->type.bit6 is set:

    if (trace->type.bit6) {
        ...
        queue = skb_get_tx_queue(dev, skb);
        qdisc = rcu_dereference(queue->qdisc);

This code can lead to an out-of-bounds access of the dev->_tx[] array
when is_input is true. In such a case, the packet is on the RX path and
skb->queue_mapping contains the RX queue index of the ingress device. If
the ingress device has more RX queues than the egress device (dev) has
TX queues, skb_get_queue_mapping(skb) will exceed dev->num_tx_queues.
Add a check to avoid this situation since skb_get_tx_queue() does not
clamp the index. This issue has also revealed that per queue visibility
cannot be accurate and will be replaced later as a new feature.

While at it, add missing lock around qdisc_qstats_qlen_backlog(). The
function __ioam6_fill_trace_data() is called from both softirq and
process contexts, hence the use of spin_lock_bh() here.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-43083?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43083?

Apply the vendor's patch.

## Is CVE-2026-43083 being exploited?

There is no known exploitation of CVE-2026-43083 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-2026-43083 and fix it if it is affected.

What it is: CVE-2026-43083 is a critical memory corruption vulnerability in Linux kernel, published on 6 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43083 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-2026-43083/ (Markdown: https://insights.sbomify.com/CVE-2026-43083/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43083
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43083
- OSV: https://osv.dev/vulnerability/CVE-2026-43083

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43083/
Summaries are generated and may contain mistakes; the official description above is the record.