net/sched: fq: clamp quantum and initial_quantum in change path (CVE-2026-90050) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90050

net/sched: fq: clamp quantum and initial_quantum in change path

Answer in brief

CVE-2026-90050 records a Unknown severity vulnerability in net/sched: fq: clamp quantum and initial_quantum in change path. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=d16dac3925be95ad46e986d4b139c9898b6e227f <a27498d34c3f429fb6db3aa609569f8154afa175 \|\| >=f6b3e3848a5fca63438984acd6d9eceac80814c1 <798283cd0fe7ba997f67e5a917f14ab40afa8d9f \|\| >=e35acd56f244d94355f9ab237c2ecc8fba5e6f04 <72e9387884554f47b03bfd40fb8b2bf52789c68d \|\| >=709f34f7c28dc4dd6c40343d101850f11e172312 <094cc07f98dfe70a34e2a1923af17fd29b8cf622	a27498d34c3f429fb6db3aa609569f8154afa175, 798283cd0fe7ba997f67e5a917f14ab40afa8d9f, 72e9387884554f47b03bfd40fb8b2bf52789c68d, 094cc07f98dfe70a34e2a1923af17fd29b8cf622
Linux/Linuxgeneric	7.3-rc1	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to a27498d34c3f429fb6db3aa609569f8154afa175 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: net/sched: fq: clamp quantum and initial_quantum in change path The fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and TCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to [1, 1<<20]. A user can override the init clamp via tc qdisc change, restoring the small-quantum deficit spin that the init clamp prevents. Narrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at parse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and fq_init() quantum to [256, 1<<20] for tiny-MTU devices. Conditions to recreate the bug: CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via unshare -Urn suffices). tc qdisc add dev dummy0 root fq tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0

Quoted source text, attributed separately from HOL analysis.