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CVE-2026-27737— BigBlueButton has Stored XSS in bbb-playback replay

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BigBlueButton社区的一套开源的Web会议系统。 BigBlueButton 3.0.19之前版本存在跨站脚本漏洞，该漏洞源于录制回放未清理公共聊天中的用户输入，可能导致跨站脚本攻击。

CVSS 6.5 · Medium EPSS 0.43% · P35

Possible ATT&CK Techniques 1 AI

T1059.007 · JavaScript

Affected Version Matrix 3

VendorProduct Version RangeStatus
bigbluebutton bbb-playback < 5.4.3 affected
bigbluebutton bigbluebutton < 3.0.19 affected
blindsidenetworks scalite < 1.7.0 affected
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I. Basic Information for CVE-2026-27737

Vulnerability Information
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Vulnerability Title
BigBlueButton has Stored XSS in bbb-playback replay
Source: CVE Program / CVE List V5
Vulnerability Description
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 the recording. This issue has been fixed 3.0.19.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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
Vulnerability Title
BigBlueButton 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
BigBlueButton是BigBlueButton社区的一套开源的Web会议系统。 BigBlueButton 3.0.19之前版本存在跨站脚本漏洞，该漏洞源于录制回放未清理公共聊天中的用户输入，可能导致跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
bigbluebutton bigbluebutton < 3.0.19 -
blindsidenetworks scalite < 1.7.0 -
bigbluebutton bbb-playback < 5.4.3 -

II. Public POCs for CVE-2026-27737

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III. Intelligence Information for CVE-2026-27737

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Patches & Fixes for CVE-2026-27737 (2)

Vendor Advisories for CVE-2026-27737 (1)

Vendor Pages for CVE-2026-27737 (1)

Other References for CVE-2026-27737 (1)

IV. Related Vulnerabilities

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

V. Comments for CVE-2026-27737

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