# CVE-2026-72297: net: atm: reject out-of-range traffic classes in QoS validation

> An attacker can trigger an out-of-bounds read in the Linux kernel ATM subsystem by supplying invalid traffic classes, potentially leaking memory contents.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-72297, DEBIAN-CVE-2026-72297, GHSA-2234-wg35-953c, UBUNTU-CVE-2026-72297

## What is CVE-2026-72297?

CVE-2026-72297 is a high-severity vulnerability in Linux, published on 15 Aug 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:

net: atm: reject out-of-range traffic classes in QoS validation

Reject ATM traffic classes above ATM_ANYCLASS in check_tp().
SO_ATMQOS stores the supplied QoS after check_qos() succeeds, so
accepting larger values leaves invalid traffic_class values in
vcc->qos.

That bad state later reaches pvc_info(), which indexes class_name[]
with vcc->qos.{rx,tp}.traffic_class. Values above ATM_ANYCLASS cause
an out-of-bounds read when /proc/net/atm/pvc is read.

Tighten the existing QoS validation so invalid traffic_class values
are rejected at the point where user supplied QoS is accepted.

## Which versions are affected by CVE-2026-72297?


## How do I fix CVE-2026-72297?

Apply the vendor's patch.

## Is CVE-2026-72297 being exploited?

There is no known exploitation of CVE-2026-72297 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72297 and fix it if it is affected.

What it is: CVE-2026-72297 is a high-severity vulnerability in Linux, published on 15 Aug 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-2026-72297 in the wild and no public exploit code.

Affected product: Linux. 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-2026-72297/ (Markdown: https://insights.sbomify.com/CVE-2026-72297/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72297
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72297
- OSV: https://osv.dev/vulnerability/CVE-2026-72297

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72297/
Summaries are generated and may contain mistakes; the official description above is the record.