---
id: CVE-2026-11812
title: 'UpdateHub: race condition on shared context causes out-of-bounds write and DoS'
summary: >-
  The UpdateHub management subsystem (subsys/mgmt/updatehub/updatehub.c) drives
  every update operation through a single file-scope ctx structure that holds
  the CoAP block context, payload buffer, status code, socket, and a one-element
  poll…
severity: low
cvss: 2.5
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-362
vendor: zephyrproject
product: zephyr
affected:
  - zephyr >= 2.0.0 < 4.3.2
  - zephyr >= 4.4.0 < 4.4.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-12T18:51:06.812463Z'
published: '2026-08-10'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T04:59:15.164Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-11812'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/551d3f92b36e9604f039101c4e4f623682d02159
    label: Fix commit
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vprh-rff6-46xp
    label: GHSA-vprh-rff6-46xp
tags:
  - cve.org
epss: 0.00104
epssPercentile: 0.01025
ingestedAt: '2026-11-05T20:33:06.697Z'
---

## Overview

The UpdateHub management subsystem (subsys/mgmt/updatehub/updatehub.c) drives every update operation through a single file-scope ctx structure that holds the CoAP block context, payload buffer, status code, socket, and a one-element poll-fd array fds[1]. Access to ctx was not serialized, and prepare_fds() wrote ctx.fds[ctx.nfds] and incremented ctx.nfds with no bounds check.

Two independent paths mutate ctx concurrently: the background autohandler running on the system workqueue, and user-triggered operations reached through the updatehub run shell command, direct API calls, or — since the operations are exposed as syscalls — userspace threads. When a second flow enters prepare_fds() while ctx.nfds is already 1, the write lands one element past the array; by struct layout it overlaps the adjacent ctx.sock/ctx.nfds members. More broadly, the unsynchronized sharing lets two flows interleave connection setup and teardown, double-closing a socket descriptor or scribbling the shared buffers.

The result is corruption of the update subsystem's internal state and denial of service of the firmware-update path; the out-of-bounds write is contained within the ctx structure and there is no demonstrated path to memory outside it or to code execution. Triggering requires a local actor able to invoke update operations (or, with CONFIG_USERSPACE, an unprivileged userspace thread) and to win a timing race against the background handler; remote peers cannot control the race timing. The fix serializes the entry points with a mutex and adds a bounds check to prepare_fds().

## Affected

- `zephyr >= 2.0.0 < 4.3.2`
- `zephyr >= 4.4.0 < 4.4.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.