[UPDATE] [medium] BigBlueButton: Multiple Vulnerabilities

mediumCVE-2026-55491 CVE-2026-55489

A remote, authenticated attacker can exploit multiple vulnerabilities in BigBlueButton to conduct a Cross-Site Scripting attack, bypass security measures and manipulate data.

CSIRTS triage

vendor: BigBlueButton product: BigBlueButton Cross-site scripting Authentication bypass

What: Multiple vulnerabilities in BigBlueButton enable authenticated attackers to conduct cross-site scripting attacks, bypass security measures, and manipulate data.
Who is affected: Authenticated users and remote attackers exploiting prior access to BigBlueButton deployments are affected.
Urgency: Medium urgency; vulnerabilities require authentication to exploit, limiting exposure compared to unauthenticated attacks.
Action: Update BigBlueButton to a patched version addressing CVE-2026-55491 and CVE-2026-55489.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: medium
Published: 2026-08-21
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-1916

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-2026-554910.17% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 6% of all EPSS-scored CVEs.
Low exploitation riskCVE-2026-554890.19% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 9% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-55491	coverage & exploitation status	NVD · CVE.org
CVE-2026-55489	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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