# CVE-2026-98013: net/sched: fq_pie: clamp quantum in change path

CVE-2026-98013 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-98013, released September 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-98013
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 25, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98013

## Description

In the Linux kernel, the following vulnerability has been resolved:  net/sched: fq_pie: clamp quantum in change path  fq_pie_change() accepts any quantum value from userspace, including 1. With a crafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times under the qdisc lock (a soft lockup / denial of service).  Add max(256U, ...) matching fq_codel_change().  Conditions to recreate the bug:   CONFIG_NET_SCH_FQ_PIE=y. Requires CAP_NET_ADMIN (namespace-local via   unshare -Urn suffices).    tc qdisc add dev dummy0 root fq_pie   tc qdisc change dev dummy0 root fq_pie quantum 1 stab data 32768 size_log 15 cell_log 0

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.190-1 | [DEBIAN-CVE-2026-98013](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98013.md) | Sep 29, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.111-1 | [DEBIAN-CVE-2026-98013](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98013.md) | Sep 29, 2026 |
| Linux | linux Debian 14 | 7.2.7-1 | [DEBIAN-CVE-2026-98013](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98013.md) | Sep 29, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.111-1~deb12u1 | [DEBIAN-CVE-2026-98013](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98013.md) | Sep 29, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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