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Authentication Bypass For Endpoints With Anonymous Access in Opencast

Critical severity GitHub Reviewed Published Jan 29, 2020 in opencast/opencast • Updated Jan 9, 2023

Package

maven org.opencastproject:opencast-kernel (Maven)

Affected versions

< 7.6
>= 8.0, < 8.1

Patched versions

7.6
8.1

Description

Impact

Using a remember-me cookie with an arbitrary username can cause Opencast to assume proper authentication for that user even if the remember-me cookie was incorrect given that the attacked endpoint also allows anonymous access.

This way, an attacker can, for example, fake a remember-me token, assume the identity of the global system administrator and request non-public content from the search service without ever providing any proper authentication.

Patches

This problem is fixed in Opencast 7.6 and Opencast 8.1

Workarounds

As a workaround for older, unpatched versions, disabling remember-me cookies in etc/security/mh_default_org.xml will mitigate the problem but will obviously also disable this feature without obvious indication. To deactivate this, remove the following line from the security configuration:

<sec:remember-me … />

References

For more information

If you have any questions or comments about this advisory:

References

@lkiesow lkiesow published to opencast/opencast Jan 29, 2020
Reviewed Jan 30, 2020
Published to the GitHub Advisory Database Jan 30, 2020
Last updated Jan 9, 2023

Severity

Critical

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(50th percentile)

Weaknesses

CVE ID

CVE-2020-5206

GHSA ID

GHSA-vmm6-w4cf-7f3x

Source code

No known source code
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