CVE-2026-4179Public exploit

Device hang via ISR scheduler yield

Published Mar 14, 2026 · Updated Mar 14, 2026

Infinite-loop DoS in Zephyr RTOS 4.3 and earlier allows local users to hang STM32 devices during USB endpoint writes. The usb_write function calls k_yield after an endpoint write returns EAGAIN, even when the STM32 HAL invokes it from an interrupt handler where scheduler yielding is forbidden. Reachability requires STM32 firmware built with the affected USB device stack and code able to provoke the retry path; execution can remain stuck until the device is reset.

CVSS severity6.1
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite-loop DoS in Zephyr RTOS 4.3 and earlier allows local users to hang STM32 devices during USB endpoint writes. The usb_write function calls k_yield after an endpoint write returns EAGAIN, even when the STM32 HAL invokes it from an interrupt handler where scheduler yielding is forbidden. Reachability requires STM32 firmware built with the affected USB device stack and code able to provoke the retry path; execution can remain stuck until the device is reset.

The record

CVE
CVE-2026-4179
Published
Mar 14, 2026
Updated
Mar 14, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-835, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=* <=4.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=* <=4.3

Published CVSS scores

6.1Zephyr ProjectCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

Public exploit references

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Technologies

Your stack

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Your stack

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