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ReviewHigh

CVE-2026-74739

Linux

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...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.08.27
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

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...

Affected product and versions

Product
Linux
Affected versions
>= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < ec5f3005586a785689fd568361b0c5925cb1548b, >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 19d114b93c94bdef70496f26685c2a6b242f41b3, >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 594a064d603202b9ee21e07679d854e5c1750cc4, >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 31f26a95eeee926946809ac456c61a3217936a62, >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < e71f8e9ed6f311410b14741f6012afe01869c0fa, >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 6d3724e616faf952c3adcf8414fc21a828ef3709, >= 4.14
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available