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Fencer Intel
medium 6.1

CVE-2020-27608 json

In BigBlueButton before 2.2.28 (or earlier), uploaded presentations are sent to clients without a Content-Type header, which allows XSS, as…

published 6y ago modified 4mo ago also EUVD-2020-20115

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

In BigBlueButton before 2.2.28 (or earlier), uploaded presentations are sent to clients without a Content-Type header, which allows XSS, as demonstrated by a .png file extension for an HTML document.

Patch / fix

  • bigbluebutton bigbluebutton 2.2.28

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Exploit prediction

0.82% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • golem.de https://www.golem.de/news/big-blue-button-das-grosse-blaue-sicherheitsrisiko-2010-151610.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.