SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-21318

In Opencast before version 9.2 there is a vulnerability in which publishing an episode with strict access rules will overwrite the currently set series access.

MEDIUM 5.4EPSS 0.71%

Does this matter?

Lower severity and a low EPSS score (0.71%). Track it; it rarely justifies an emergency change on its own.

Description

Opencast is a free, open-source platform to support the management of educational audio and video content. In Opencast before version 9.2 there is a vulnerability in which publishing an episode with strict access rules will overwrite the currently set series access. This allows for an easy denial of access for all users without superuser privileges, effectively hiding the series. Access to series and series metadata on the search service (shown in media module and player) depends on the events published which are part of the series. Publishing an event will automatically publish a series and update access to it. Removing an event or republishing the event should do the same. Affected versions of Opencast may not update the series access or remove a published series if an event is being removed. On removal of an episode, this may lead to an access control list for series metadata with broader access rules than the merged access rules of all remaining events, or the series metadata still being available although all episodes of that series have been removed. This problem is fixed in Opencast 9.2.

CVSS 3.1
5.4 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
EPSS
0.71% probability · 53th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-863
Affected
apereo/opencast
Source
security-advisories@github.com
EPSS trend
0%3%5%26 October 2026: 0.71%26 October 202626 October 2026

EPSS 0.7% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.