CVE-2026-90075Hinoki check available

Soft lockup via unclamped scheduler MTU

Published Sep 17, 2026 · Updated Sep 17, 2026

Integer overflow in Linux kernel fq_codel allows local users to hang the kernel via an oversized network-device MTU. In net/sched/sch_fq_codel.c, fq_codel_init() copies an unclamped device MTU into the scheduling quantum, overflowing the signed flow deficit during dequeue and causing an infinite loop. Exploitation requires CAP_NET_ADMIN in a user namespace and a device accepting a sign-bit-crossing MTU; the same oversized CoDel parameter also disables congestion drops and ECN marking.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Get started

Summary

What happened

Integer overflow in Linux kernel fq_codel allows local users to hang the kernel via an oversized network-device MTU. In net/sched/sch_fq_codel.c, fq_codel_init() copies an unclamped device MTU into the scheduling quantum, overflowing the signed flow deficit during dequeue and causing an infinite loop. Exploitation requires CAP_NET_ADMIN in a user namespace and a device accepting a sign-bit-crossing MTU; the same oversized CoDel parameter also disables congestion drops and ECN marking.

The record

CVE
CVE-2026-90075
Published
Sep 17, 2026
Updated
Sep 17, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.5
  2. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <324f86806673ae4a55f66d28db84577f46f615e1
  3. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <3782067ec0d485628b6f1f9ede3eeeb4f611fcf2
  4. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <397e2b1f71d9f15b8b4e47d24eb620e4dff8878d
  5. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9
  6. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <a9a5b2943a00df2ab81a2209f31dd9e87016f120
  7. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <d315ee8a07fd1810880227319cf60e6cd925ef22
  8. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <d9ebd8f9aa8b2773235889cb903fafd61f2d8585
  9. Affected versionversion=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <dfb4b61db886917244284b18b44b23d2254b82c2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.5; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <324f86806673ae4a55f66d28db84577f46f615e1; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <3782067ec0d485628b6f1f9ede3eeeb4f611fcf2; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <397e2b1f71d9f15b8b4e47d24eb620e4dff8878d; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <a9a5b2943a00df2ab81a2209f31dd9e87016f120; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <d315ee8a07fd1810880227319cf60e6cd925ef22; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <d9ebd8f9aa8b2773235889cb903fafd61f2d8585; version=4b549a2ef4bef9965d97cbd992ba67930cd3e0fe <dfb4b61db886917244284b18b44b23d2254b82c2

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Get started