CVE-2026-46353: 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

highCVSS 8.1CVE-2026-46353

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 8.1
Published: 2026-07-16
Last updated: 2026-07-17
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-46353

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-463530.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 18% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-46353	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[UPDATE] [high] BigBlueButton: Multiple vulnerabilitiescert-bund

Recent advisories for BigBlueButton is an

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[UPDATE] [high] BigBlueButton: Multiple vulnerabilitiescert-bund · 2026-07-17
mediumCVE-2026-46404: BigBlueButton is an open-source virtual classroom. Prior to 3.0.23, the presentation URL valid…nvd · 2026-07-16
highCVE-2026-46351: BigBlueButton is an open-source virtual classroom. Prior to 3.0.21, bbb-web generated conferen…nvd · 2026-07-16