net/sched: reject overly deep qdisc hierarchies

Answer in brief

CVE-2026-74663 records a Unknown severity vulnerability in net/sched: reject overly deep qdisc hierarchies. 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 Aug 22, 2026Updated Aug 22, 2026Source checked Aug 22, 2026First seen by HOL Aug 22, 2026Material review Aug 22, 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	>=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9f69bb9fdaa2fe64b68bb62fb84d405784bee540 \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8ca8cdb74939581339e1ae370193c0adb5a85336 \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2759acf08a3454866660edcd3ef4e64139f254a6 \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a4b14a4df29d36458a943f9b521ddd0f940363cc \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e2d658c6427844cee5bc654b436ca68d680b6148 \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01	9f69bb9fdaa2fe64b68bb62fb84d405784bee540, 8ca8cdb74939581339e1ae370193c0adb5a85336, 2759acf08a3454866660edcd3ef4e64139f254a6, a4b14a4df29d36458a943f9b521ddd0f940363cc, e2d658c6427844cee5bc654b436ca68d680b6148, dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01
Linux/Linuxgeneric	2.6.12	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 9f69bb9fdaa2fe64b68bb62fb84d405784bee540 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 22, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: net/sched: reject overly deep qdisc hierarchies Deep qdisc hierarchies can lead to excessive recursion in qdisc tree walkers and exhaust the kernel stack. The existing loop check does not cover the create-and-graft path, so a hierarchy can still be extended by creating a new child qdisc below an already deep parent. Store the hierarchy depth in struct Qdisc and update it when qdiscs are grafted. Reject new child qdiscs once the parent is already at the maximum allowed depth.

Quoted source text, attributed separately from HOL analysis.