CVE-2026-74739

High

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.

Package Linux Kernel
Published 2026-08-26
Last modified 2026-08-27
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected versions

Linux kernel versions 4.14 and later are affected. Fixed in 6.1.184, 6.6.153, 6.12.105, 6.18.46, 7.1.10, 7.2 and their respective stable series.

Affected from
≥ 4.14
Fixed in
✓ 6.1.184 6.1.x ✓ 6.6.153 6.6.x ✓ 6.12.105 6.12.x ✓ 6.18.46 6.18.x ✓ 7.1.10 7.1.x ✓ 7.2

References

6 total
Showing 5 of 6 references View all on NVD

Frequently asked questions

  • What is CVE-2026-74739?

    CVE-2026-74739 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 . It affects Linux kernel versions from 4.14 onward and has been patched in 6.1.184, 6.6.153, 6.12.105 and others. CVE-2026-74739 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-74739?

    CVE-2026-74739 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2026-74739?

    Yes. CVE-2026-74739 has been patched. Fixed versions include 6.1.184, 6.6.153, 6.12.105 and others. If you are running Linux kernel 4.14 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-74739 actively exploited?

    No. CVE-2026-74739 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Back to
All CVEs
View on
NVD / NIST