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CVE-2026-55491— BigBlueButton: Stored XSS in Screenshare Recording Playback via Unescaped Meeting Name

Quick assessment

Affected
bigbluebutton bigbluebutton
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

BigBlueButton 是一款开源的虚拟教室平台。在 3.0.29 版本之前，BigBlueButton 在生成屏幕共享回放格式时，未能正确转义 文件中的 变量。低权限用户可以构造一个嵌入恶意脚本内容的会议名称，当其他用户回放该会议录像时，该脚本将在其浏览器中执行。此问题已在 3.0.29 版本中修复。

CVSS 5.4 · Medium EPSS 0.17% · P6

Affected Version Matrix 1

VendorProduct Version RangeStatus
bigbluebutton bigbluebutton < 3.0.29 affected
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I. Basic Information for CVE-2026-55491

Vulnerability Information
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Vulnerability Title
BigBlueButton: Stored XSS in Screenshare Recording Playback via Unescaped Meeting Name
Source: CVE Program / CVE List V5
Vulnerability Description
BigBlueButton is an open-source virtual classroom. Prior to 3.0.29, BigBlueButton failed to escape meetingName in record-and-playback/screenshare/playback/index.html.erb when generating the screenshare playback format. A low-privileged user could store a crafted meeting name that embedded script content, and the script executed in another user's browser when that user replayed the recording. This issue is fixed in version 3.0.29.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
bigbluebutton bigbluebutton < 3.0.29 -

II. Public POCs for CVE-2026-55491

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III. Intelligence Information for CVE-2026-55491

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Patches & Fixes for CVE-2026-55491 (1)

Vendor Advisories for CVE-2026-55491 (1)

Vendor Pages for CVE-2026-55491 (1)

Same Patch Batch · bigbluebutton · 2026-08-20 · 4 CVEs total

CVE-2026-46682 8.5 HIGH BigBlueButton: Blind SQL Injection AUTH (Moderator)
CVE-2026-46355 7.1 HIGH BigBlueButton: Unauthenticated Session Hijack via Exposed /bigbluebutton/api/handleJoinExi
CVE-2026-55489 4.9 MEDIUM BigBlueButton: IDOR on BBB through /api/graphql via POST parameter "presentationId" leads

IV. Related Vulnerabilities

Same product: bigbluebutton
Same vendor: bigbluebutton
Same weakness: CWE-79

V. Comments for CVE-2026-55491

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