Description
Opencast is a free, open-source platform to support the management of educational audio and video content. Prior to versions 19.7 and 20.2, the default security configuration in etc/security/mh_default_org.xml accepts a client-selected JSESSIONID from the ;jsessionid= URL path parameter and does not replace it when the victim logs in. An unauthenticated attacker can send a crafted link to a victim whose browser has no active Opencast session cookie, wait for the victim to authenticate, and then reuse the known identifier as the victim's authenticated session. This can expose the victim's data and actions and can produce full administrative account takeover when the victim is an administrator. This issue is fixed in versions 19.7 and 20.2.
References6
- github.com/opencast/opencast/commit/c36652250a026afb7cf78b66395…
- github.com/opencast/opencast/commit/ff84128c9b3bcbd79c28192d259…
- github.com/opencast/opencast/releases/tag/19.7
- github.com/opencast/opencast/releases/tag/20.2
- github.com/opencast/opencast/security/advisories/GHSA-6f53-jp7x…
- github.com/opencast/opencast/security/advisories/GHSA-6f53-jp7x…
Metrics
- CVSS 3.1
-
8.8
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 46 · as of 8 November 2026
- CWE
- CWE-384
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.