---
id: CVE-2026-98234
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: hhf: cap hh_flows_limit at change time

  hhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: hhf: cap hh_flows_limit at change time

  hhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge
  hh_flows_limit lets each new heavy-hitter flow…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    7adfd0a42174b85c6bd678858ecd6674f403f336
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    35fd423a5c5132c6f4321f6c4f0a7b4b90af830c
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    06d2a101e89063cb0b9b459104db48bdfb0a797d
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    d8e2f1f0263b7c97b222c06070cccf13e0ab7112
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    1731ff1d20489afe4cd01b7d16d37f324746ac54
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    f6547d27ce2093c5627636fb63dd0b7523c466f9
  - >-
    Linux >= 10239edf86f137ce4c39b62ea9575e8053c549a0 <
    2cef2588c995722a901368def30befeef9ae55c6
  - Linux 3.14
published: '2026-10-06'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T09:18:11.033'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98234'
references:
  - url: 'https://git.kernel.org/stable/c/06d2a101e89063cb0b9b459104db48bdfb0a797d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1731ff1d20489afe4cd01b7d16d37f324746ac54'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2cef2588c995722a901368def30befeef9ae55c6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/35fd423a5c5132c6f4321f6c4f0a7b4b90af830c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7adfd0a42174b85c6bd678858ecd6674f403f336'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d8e2f1f0263b7c97b222c06070cccf13e0ab7112'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f6547d27ce2093c5627636fb63dd0b7523c466f9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-06T08:50:17.435Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

net/sched: hhf: cap hh_flows_limit at change time

hhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge
hh_flows_limit lets each new heavy-hitter flow pass the
hh_flows_current_cnt check in alloc_new_hh() and forces a fixed-size
kzalloc(GFP_ATOMIC) per flow under spoofed traffic, for unbounded memory
growth.

Bound the attribute with NLA_POLICY_MAX() at 2*HH_FLOWS_CNT (the
hhf_init() default) and report the rejected value via extack. The
deprecated nested parse is kept: legacy tc does not set NLA_F_NESTED on
TCA_OPTIONS. Configs relying on hh_limit above the default were relying
on unbounded, unsafe behaviour and are not supported going forward.

hhf_init() also ran hhf_change() before setting the default
hh_flows_limit, so a user-supplied hh_limit at add time was clobbered
back to 2048. Set the default before hhf_change() so the configured
value sticks.

This is a follow-up to commit eb56a495f59b ("net/sched: hhf: clamp
quantum in change and init paths"), which bounded the quantum of the
same qdisc; the hh_flows_limit bound is the remaining unbounded knob of
that series' scope.

Conditions to recreate the bug: CAP_NET_ADMIN in a user namespace;
tc qdisc change dev X root hhf hh_limit 4294967295 succeeds and the
value is echoed by tc qdisc show, unbounding heavy-hitter flow
allocations; also tc qdisc add dev X root hhf hh_limit 500 stores 2048
instead of 500.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.