CVE-2026-42091 — Arbitrary File Access

title: CVE-2026-42091 - goshs Arbitrary File Write via PUT
id: scw-2026-05-04-ai-1
status: experimental
level: critical
description: |
  Detects the use of the HTTP PUT method on the root path ('/') of a goshs server, which is indicative of the arbitrary file write vulnerability exploited in CVE-2026-42091. This bypasses network isolation by allowing an attacker-controlled website to write files to a goshs instance via a victim's browser.
author: SCW Feed Engine (AI-generated)
date: 2026-05-04
references:
  - https://shimiscyberworld.com/posts/nvd-CVE-2026-42091/
tags:
  - attack.initial_access
  - attack.t1190
logsource:
    category: webserver
detection:
  selection:
      cs-method:
          - 'PUT'
      cs-uri:
          - '/'
      condition: selection
falsepositives:
  - Legitimate administrative activity

Source: Shimi's Cyber World · License & reuse