CVE-2026-27737 — Cross-Site Scripting (XSS)
CVE-2026-27737 — BigBlueButton is an open-source virtual classroom. In versions prior to 3.0.19, the recording playback (presentation format) was not sanitizing user's input in public chat. This allowed for a malicious actor to craft and carry out a targeted XSS attack, activated on anyone replaying
What This Means For You
- If your environment is affected by CWE-79, review your exposure and prioritize patching based on your environment. Monitor vendor advisories for CVE-2026-27737 updates and patches.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
BigBlueButton XSS via Public Chat Recording Playback — CVE-2026-27737
title: BigBlueButton XSS via Public Chat Recording Playback — CVE-2026-27737
id: scw-2026-05-18-ai-1
status: experimental
level: high
description: |
Detects attempts to exploit CVE-2026-27737 by observing web requests to the BigBlueButton recording playback endpoint that contain a known XSS payload within the query string. This indicates an attempt to inject malicious script into the chat playback, which would execute when another user replays the recording.
author: SCW Feed Engine (AI-generated)
date: 2026-05-18
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-27737/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/bigbluebutton/playback/'
cs-uri-query|contains:
- '<script>alert('CVE-2026-27737')</script>'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-27737 | vulnerability | CVE-2026-27737 |
| CWE-79 | weakness | CWE-79 |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 19, 2026 at 01:16 UTC |
This content was curated and summarized by Shimi's Cyber World for informational purposes. It is not copied or republished in full. All intellectual property rights remain with the original author and source.
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