CVE-2020-12443

Name: CVE-2020-12443
Creator: NVD / NIST
Published: 2020-04-29T02:15:11.467+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.57%

Last modified Jun 17, 2026

CVE-2020-12443 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value can be a .pdf filename while the presFilename (mixed case) value has a ../ sequence. This can be leveraged for privilege escalation via a directory traversal to bigbluebutton.properties. EPSS estimates a 3.57% chance of exploitation in the next 30 days.

Description

BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value can be a .pdf filename while the presFilename (mixed case) value has a ../ sequence. This can be leveraged for privilege escalation via a directory traversal to bigbluebutton.properties. NOTE: this issue exists because of an ineffective mitigation to CVE-2020-12112 in which there was an attempted fix within an NGINX configuration file, without considering that the relevant part of NGINX is case-insensitive.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.57%

87.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

Affected Software

Vendor	Product	Versions
Bigbluebutton	Bigbluebutton	< 2.2.6

References

https://github.com/bigbluebutton/bigbluebutton/pull/9259/commits/b21ca8355a57286a1e6df96984b3a4c57679a463Patch, Third Party Advisory
https://github.com/mclab-hbrs/BBB-POCExploit, Third Party Advisory
https://github.com/bigbluebutton/bigbluebutton/pull/9259/commits/b21ca8355a57286a1e6df96984b3a4c57679a463Patch, Third Party Advisory
https://github.com/mclab-hbrs/BBB-POCExploit, Third Party Advisory

Timeline

Published: Apr 29, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12443?

How severe is CVE-2020-12443?

CVE-2020-12443 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.57% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12443?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-12443?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST