How severe is CVE-2021-43794?

CVE-2021-43794 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-43794 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43794?

CVE-2021-43794 affects Discourse. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43794?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-43794 published?

CVE-2021-43794 was published on 2021-12-01 and last updated on 2026-06-17.

CVE-2021-43794

CVE-2021-43794 is a medium-severity vulnerability in Discourse with a CVSS 3.x base score of 5.3. 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-610.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-610
Affected product: Discourse
Published: 2021-12-01
Last modified: 2026-06-17

Description

Discourse is an open source discussion platform. In affected versions an attacker can poison the cache for anonymous (i.e. not logged in) users, such that the users are shown a JSON blob instead of the HTML page. This can lead to a partial denial-of-service. This issue is patched in the latest stable, beta and tests-passed versions of Discourse.

Frequently asked questions

What is CVE-2021-43794?: Discourse is an open source discussion platform. In affected versions an attacker can poison the cache for anonymous (i.e. not logged in) users, such that the users are shown a JSON blob instead of the HTML page. This can lead to a partial denial-of-service. This issue is patched in the latest stable, beta and tests-passed versions of Discourse.
How severe is CVE-2021-43794?: CVE-2021-43794 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-43794 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43794?: CVE-2021-43794 affects Discourse. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43794?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-43794 published?: CVE-2021-43794 was published on 2021-12-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*

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