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CVE-2026-90072 Affecting kernel-tools-devel package, versions <1:6.1.188-233.385.amzn2023

Severity

 Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.22% (12th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNELTOOLSDEVEL-20869444
  • published13 Oct 2026
  • disclosed17 Sept 2026
Report a new vulnerability Found a mistake?

Introduced: 17 Sep 2026

NewCVE-2026-90072  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel-tools-devel to version 1:6.1.188-233.385.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3197.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-tools-devel package and not the kernel-tools-devel 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: sfq: clamp quantum to avoid signed overflow soft lockup

sfq_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) (unsigned). A device with a huge MTU (e.g. dummy with max_mtu == 0 accepting MTU 2147483634) makes psched_mtu() return 0x80000000, so slot->allot = INT_MIN and INT_MIN + INT_MIN toggles between INT_MIN and 0 forever, spinning sfq_dequeue() under the qdisc lock.

Clamp the quantum to [256, 1 << 20] so the refill loop terminates. The lower bound also covers q->quantum == 0 (psched_mtu() returning 0), which spins sfq_dequeue() identically. sfq_change() already rejects a negative quantum, so only the init path was exposed.

Conditions to recreate the bug: a device whose MTU (plus hard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy device with max_mtu == 0 accepting MTU 2147483634). Requires CAP_NET_ADMIN in a user namespace.