CVE-2026-5340 — Cross-Site Scripting (XSS)

title: WordPress Fancy Image Show Stored XSS via Shortcode — CVE-2026-5340
id: scw-2026-05-12-ai-1
status: experimental
level: medium
description: |
  Detects attempts to exploit CVE-2026-5340 in the Fancy Image Show WordPress plugin. This rule looks for requests to the plugin's directory containing the 'fancy-img-show' shortcode and common XSS payload patterns within the URI query. This indicates a potential stored XSS attack where an attacker with contributor-level access injects scripts into pages.
author: SCW Feed Engine (AI-generated)
date: 2026-05-12
references:
  - https://shimiscyberworld.com/posts/nvd-CVE-2026-5340/
tags:
  - attack.initial_access
  - attack.t1190
logsource:
    category: webserver
detection:
  selection:
      cs-uri|contains:
          - '/wp-content/plugins/fancy-img-show/'
      cs-uri-query|contains:
          - 'fancy-img-show'
      cs-uri-query|contains:
          - '" onmouseover="alert('CVE-2026-5340')"'
      cs-uri-query|contains:
          - '" onclick="alert('CVE-2026-5340')"'
  condition: selection
falsepositives:
  - Legitimate administrative activity

Source: Shimi's Cyber World · License & reuse