CVE-2026-21789 — HCL Connections contains a broken access control

title: CVE-2026-21789 - HCL Connections Unauthorized Data Update via Broken Access Control
id: scw-2026-05-18-ai-1
status: experimental
level: medium
description: |
  Detects attempts to update data in HCL Connections by sending PUT requests to specific resource URIs, indicative of exploiting the CVE-2026-21789 broken access control vulnerability. This rule specifically targets the known vulnerable path and HTTP method used to potentially modify unauthorized data.
author: SCW Feed Engine (AI-generated)
date: 2026-05-18
references:
  - https://shimiscyberworld.com/posts/nvd-CVE-2026-21789/
tags:
  - attack.initial_access
  - attack.t1190
logsource:
    category: webserver
detection:
  selection:
      cs-uri|contains:
          - '/connections/resources/communities/'
      cs-method:
          - 'PUT'
      sc-status:
          - '200'
      condition: selection
falsepositives:
  - Legitimate administrative activity

Source: Shimi's Cyber World · License & reuse