Out-of-bounds Read Affecting kernel-tools-debuginfo package, versions <1:6.1.186-228.374.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.14% (4th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNELTOOLSDEBUGINFO-19817255
  • published15 Sept 2026
  • disclosed26 Aug 2026

Introduced: 26 Aug 2026

NewCVE-2026-74739  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel-tools-debuginfo to version 1:6.1.186-228.374.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2143.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-tools-debuginfo package and not the kernel-tools-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1