CVE-2021-21318

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. Limited direct impact.

Exploit odds

0.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-02-18 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:35 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.7% in the next 30 days (EPSS).
• Severity: 5.4 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-02-18 18:15 UTC

Last modified

2026-06-17 03:35 UTC

Exploit probability

0.7% · EPSS, next 30 days

Weakness

CWE-863 · Incorrect authorization

Record status

Modified

Affected

• Apereo Opencast < 9.2

Attack profile CVSS 3.1 · 5.4

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-21318.md and follow it. Check whether this project is affected by CVE-2021-21318. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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