How severe is CVE-2021-39183?

CVE-2021-39183 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity high, and availability low.

Is CVE-2021-39183 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39183?

CVE-2021-39183 affects Owncast Project Owncast. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39183?

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-2021-39183 published?

CVE-2021-39183 was published on 2021-12-14 and last updated on 2026-06-17.

CVE-2021-39183

CVE-2021-39183 is a high-severity vulnerability in Owncast Project Owncast with a CVSS 3.x base score of 8.2. 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-79.

Key facts

Severity: High (CVSS 3.x base score 8.2)
CVSS v2: 4.3
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Owncast Project Owncast
Published: 2021-12-14
Last modified: 2026-06-17

Description

Owncast is an open source, self-hosted live video streaming and chat server. In affected versions inline scripts are executed when Javascript is parsed via a paste action. This issue is patched in 0.0.9 by blocking unsafe-inline Content Security Policy and specifying the script-src. The worker-src is required to be set to blob for the video player.

Frequently asked questions

What is CVE-2021-39183?: Owncast is an open source, self-hosted live video streaming and chat server. In affected versions inline scripts are executed when Javascript is parsed via a paste action. This issue is patched in 0.0.9 by blocking unsafe-inline Content Security Policy and specifying the script-src. The worker-src is required to be set to blob for the video player.
How severe is CVE-2021-39183?: CVE-2021-39183 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity high, and availability low.
Is CVE-2021-39183 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39183?: CVE-2021-39183 affects Owncast Project Owncast. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39183?: 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-2021-39183 published?: CVE-2021-39183 was published on 2021-12-14 and last updated on 2026-06-17.

References

https://github.com/owncast/owncast/security/advisories/GHSA-2hfj-cxw7-g45p

Affected products (1)

cpe:2.3:a:owncast_project:owncast:*:*:*:*:*:*:*:*

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