CVE-2020-12443
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.57%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 3.57% probability · 89th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-22
- Affected
- bigbluebutton/bigbluebutton
- Source
- cve@mitre.org
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.