---
id: CVE-2026-49140
title: Nanobot < 0.2.1 Denial of Service via Matrix Media Download Handler
summary: >-
  Nanobot prior to version 0.2.1 contains a denial of service vulnerability in
  the Matrix channel media download handler that allows authenticated room
  members to exhaust process memory and bandwidth by sending media events with
  missing or…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-770
vendor: HKUDS
product: nanobot
affected:
  - nanobot < 0.2.1
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-02T12:34:52.411238Z'
exploitAvailable: true
published: '2026-06-01'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:04:48.867Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-49140'
references:
  - url: 'https://github.com/HKUDS/nanobot/releases/tag/v0.2.1'
    label: nanobot 0.2.1 Release Notes
  - url: 'https://github.com/HKUDS/nanobot/pull/4106'
  - url: >-
      https://github.com/HKUDS/nanobot/commit/1d4000560dfff1acb83f5c5ca8ef3ab1f092bd14
  - url: >-
      https://www.vulncheck.com/advisories/nanobot-denial-of-service-via-matrix-media-download-handler
tags:
  - cve.org
  - exploit-available
epss: 0.00268
epssPercentile: 0.19058
ingestedAt: '2026-11-08T14:51:22.386Z'
---

## Overview

Nanobot prior to version 0.2.1 contains a denial of service vulnerability in the Matrix channel media download handler that allows authenticated room members to exhaust process memory and bandwidth by sending media events with missing or invalid size metadata. Attackers can send multiple concurrent Matrix media events with omitted or invalid declared sizes to trigger simultaneous large media downloads that fully materialize response bodies before post-download rejection, consuming process resources until service degradation occurs.

## Affected

- `nanobot < 0.2.1`

## Remediation

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