CVE-2026-41126Network attack vector

User redirection via invalid-checksum logoutURL

Published Apr 21, 2026 · Updated Apr 21, 2026

Open redirect in BigBlueButton before 3.0.24 allows remote attackers to send users to an untrusted site through a crafted join request. The /bigbluebutton/api/join handler retains an attacker-controlled logoutURL when the request checksum is invalid instead of replacing it with the configured default. Exploitation requires a user to open the crafted join link, after which the affected client follows the malicious redirect; no server-side data modification or service interruption is reported.

CVSS severity4.3
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in BigBlueButton before 3.0.24 allows remote attackers to send users to an untrusted site through a crafted join request. The /bigbluebutton/api/join handler retains an attacker-controlled logoutURL when the request checksum is invalid instead of replacing it with the configured default. Exploitation requires a user to open the crafted join link, after which the affected client follows the malicious redirect; no server-side data modification or service interruption is reported.

The record

CVE
CVE-2026-41126
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
BigBlueButton Inc.
Product
BigBlueButton
Classifications
CWE-601, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.0.24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BigBlueButton Inc. · BigBlueButtonversion=< 3.0.24

Published CVSS scores

4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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