How severe is CVE-2021-43807?

CVE-2021-43807 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-43807 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43807?

CVE-2021-43807 affects Apereo Opencast. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43807?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-43807 published?

CVE-2021-43807 was published on 2021-12-14 and last updated on 2026-06-17.

CVE-2021-43807

CVE-2021-43807 is a high-severity vulnerability in Apereo Opencast with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-290.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-290
Affected product: Apereo Opencast
Published: 2021-12-14
Last modified: 2026-06-17

Description

Opencast is an Open Source Lecture Capture & Video Management for Education. Opencast versions prior to 9.10 allow HTTP method spoofing, allowing to change the assumed HTTP method via URL parameter. This allows attackers to turn HTTP GET requests into PUT requests or an HTTP form to send DELETE requests. This bypasses restrictions otherwise put on these types of requests and aids in cross-site request forgery (CSRF) attacks, which would otherwise not be possible. The vulnerability allows attackers to craft links or forms which may change the server state. This issue is fixed in Opencast 9.10 and 10.0. You can mitigate the problem by setting the `SameSite=Strict` attribute for your cookies. If this is a viable option for you depends on your integrations. We strongly recommend updating in any case.

Frequently asked questions

What is CVE-2021-43807?: Opencast is an Open Source Lecture Capture & Video Management for Education. Opencast versions prior to 9.10 allow HTTP method spoofing, allowing to change the assumed HTTP method via URL parameter. This allows attackers to turn HTTP GET requests into PUT requests or an HTTP form to send DELETE requests. This bypasses restrictions otherwise put on these types of requests and aids in cross-site request forgery (CSRF) attacks, which would otherwise not be possible. The vulnerability allows attackers to craft links or forms which may change the server state. This issue is fixed in Opencast 9.10 and 10.0. You can mitigate the problem by setting the `SameSite=Strict` attribute for your cookies. If this is a viable option for you depends on your integrations. We strongly recommend updating in any case.
How severe is CVE-2021-43807?: CVE-2021-43807 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-43807 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43807?: CVE-2021-43807 affects Apereo Opencast. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43807?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-43807 published?: CVE-2021-43807 was published on 2021-12-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apereo:opencast:*:*:*:*:*:*:*:*

More vulnerabilities in Apereo Opencast

CVE-2021-43821 — Critical (CVSS 9.9): Opencast is an Open Source Lecture Capture & Video Management for Education. Opencast before version 9.10 or 10.6…
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CVE-2020-5229 — High (CVSS 7.7): Opencast before 8.1 stores passwords using the rather outdated and cryptographically insecure MD5 hash algorithm.…
CVE-2020-5228 — High (CVSS 7.6): Opencast before 8.1 and 7.6 allows unauthorized public access to all media and metadata by default via OAI-PMH. OAI-PMH…

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