CVE-2026-46353

BigBlueButton API checksum bypass via presentationUploadExternalUrl

HIGH
8.1
CVSS Score
Published: July 16, 2026 at 06:06 PM UTC
Updated: July 17, 2026 at 07:55 PM UTC
1 product affected across 1 vendorBigbluebutton

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Severity
HIGH8.1
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web checksum validation could be bypassed when a presentationUploadExternalUrl parameter was supplied to API request handling in CreateMeeting.java and ValidationService.java, allowing a user to send valid requests to some endpoints without a checksum. This issue is fixed in version 3.0.21.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.0.21
Affected range stops below 3.0.21, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-284

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