How severe is CVE-2021-43850?

CVE-2021-43850 has a CVSS 3.x base score of 6.8, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-43850 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43850?

CVE-2021-43850 primarily affects Discourse. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-43850?

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

When was CVE-2021-43850 published?

CVE-2021-43850 was published on 2022-01-04 and last updated on 2026-06-17.

CVE-2021-43850

CVE-2021-43850 is a medium-severity vulnerability in Discourse with a CVSS 3.x base score of 6.8. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 6.8)
CVSS v2: 4.0
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Discourse
Published: 2022-01-04
Last modified: 2026-06-17

Description

Discourse is an open source platform for community discussion. In affected versions admins users can trigger a Denial of Service attack via the `/message-bus/_diagnostics` path. The impact of this vulnerability is greater on multisite Discourse instances (where multiple forums are served from a single application server) where any admin user on any of the forums are able to visit the `/message-bus/_diagnostics` path. The problem has been patched. Please upgrade to 2.8.0.beta10 or 2.7.12. No workarounds for this issue exist.

Frequently asked questions

What is CVE-2021-43850?: Discourse is an open source platform for community discussion. In affected versions admins users can trigger a Denial of Service attack via the `/message-bus/_diagnostics` path. The impact of this vulnerability is greater on multisite Discourse instances (where multiple forums are served from a single application server) where any admin user on any of the forums are able to visit the `/message-bus/_diagnostics` path. The problem has been patched. Please upgrade to 2.8.0.beta10 or 2.7.12. No workarounds for this issue exist.
How severe is CVE-2021-43850?: CVE-2021-43850 has a CVSS 3.x base score of 6.8, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-43850 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43850?: CVE-2021-43850 primarily affects Discourse. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-43850?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-43850 published?: CVE-2021-43850 was published on 2022-01-04 and last updated on 2026-06-17.

References

Affected products (10)

cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta1:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta2:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta3:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta4:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta5:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta6:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta7:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta8:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2.8.0:beta9:*:*:*:*:*:*

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