net/sched: cls_u32: skip hash tables in u32_bind_class() (CVE-2026-74739) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-74739

net/sched: cls_u32: skip hash tables in u32_bind_class()

Answer in brief

CVE-2026-74739 records a Unknown severity vulnerability in net/sched: cls_u32: skip hash tables in u32_bind_class(). 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 26, 2026Updated Aug 26, 2026Source checked Aug 26, 2026First seen by HOL Aug 26, 2026Material review Aug 26, 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	>=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <ec5f3005586a785689fd568361b0c5925cb1548b \|\| >=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <19d114b93c94bdef70496f26685c2a6b242f41b3 \|\| >=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <594a064d603202b9ee21e07679d854e5c1750cc4 \|\| >=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <31f26a95eeee926946809ac456c61a3217936a62 \|\| >=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <e71f8e9ed6f311410b14741f6012afe01869c0fa \|\| >=07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 <6d3724e616faf952c3adcf8414fc21a828ef3709	ec5f3005586a785689fd568361b0c5925cb1548b, 19d114b93c94bdef70496f26685c2a6b242f41b3, 594a064d603202b9ee21e07679d854e5c1750cc4, 31f26a95eeee926946809ac456c61a3217936a62, e71f8e9ed6f311410b14741f6012afe01869c0fa, 6d3724e616faf952c3adcf8414fc21a828ef3709
Linux/Linuxgeneric	4.14	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to ec5f3005586a785689fd568361b0c5925cb1548b if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 26, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: skip hash tables in u32_bind_class() u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class(). The issue can be reproduced with the following commands: tc qdisc add dev lo root handle 1: hfsc tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1 tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit Fix this by skipping hash tables via the TC_U32_KEY(handle) check.

Quoted source text, attributed separately from HOL analysis.