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CVE-2026-46351— BigBlueButton: Insecure Randomness allows to guess user's conference session token and impersonate them

Quick assessment

Affected
bigbluebutton bigbluebutton
Exploitation
Public or AI PoC available; prioritize validation
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社区开源的一套开源的Web会议系统。 BigBlueButton 3.0.21之前版本存在加密问题漏洞，该漏洞源于bbb-web生成conference sessionToken值时随机性不足，可能导致会话用户预测其他用户的会议会话令牌并冒充他们。

CVSS 8.1 · High EPSS 0.46% · P38

Possible ATT&CK Techniques 1 AI

T1133 · External Remote Services

Affected Version Matrix 1

VendorProduct Version RangeStatus
bigbluebutton bigbluebutton < 3.0.21 affected
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I. Basic Information for CVE-2026-46351

Vulnerability Information
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Vulnerability Title
BigBlueButton: Insecure Randomness allows to guess user's conference session token and impersonate them
Source: CVE Program / CVE List V5
Vulnerability Description
BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web generated conference sessionToken values with insufficiently secure randomness in bbb-common-web/src/main/java/org/bigbluebutton/api/Util.java and bigbluebutton-web/grails-app/controllers/org/bigbluebutton/web/controllers/ApiController.groovy, allowing a session user to predict other users' conference session tokens and impersonate them. This issue is fixed in version 3.0.21.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用不充分的随机数
Source: CVE Program / CVE List V5
Vulnerability Title
BigBlueButton 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
BigBlueButton是BigBlueButton社区开源的一套开源的Web会议系统。 BigBlueButton 3.0.21之前版本存在加密问题漏洞，该漏洞源于bbb-web生成conference sessionToken值时随机性不足，可能导致会话用户预测其他用户的会议会话令牌并冒充他们。
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 < 3.0.21 -

II. Public POCs for CVE-2026-46351

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 9655 chars
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III. Intelligence Information for CVE-2026-46351

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Patches & Fixes for CVE-2026-46351 (1)

Vendor Advisories for CVE-2026-46351 (1)

Vendor Pages for CVE-2026-46351 (1)

Same Patch Batch · bigbluebutton · 2026-07-16 · 3 CVEs total

CVE-2026-46353 8.1 HIGH BigBlueButton API checksum bypass via presentationUploadExternalUrl
CVE-2026-46404 6.8 MEDIUM BigBlueButton: Presentation URL Security Hardening

IV. Related Vulnerabilities

Same product: bigbluebutton
Same vendor: bigbluebutton
Same weakness: CWE-330

V. Comments for CVE-2026-46351

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