How severe is CVE-2026-27021?

CVE-2026-27021 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 low, integrity none, and availability none.

Is CVE-2026-27021 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27021?

CVE-2026-27021 primarily affects Discourse. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-27021?

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

Does CVE-2026-27021 have an EU (EUVD) identifier?

Yes. CVE-2026-27021 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8887.

When was CVE-2026-27021 published?

CVE-2026-27021 was published on 2026-02-26 and last updated on 2026-06-17.

CVE-2026-27021

CVE-2026-27021 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-862.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 6.9
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8887
Weakness: CWE-862
Affected product: Discourse
Published: 2026-02-26
Last modified: 2026-06-17

Description

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, the voters endpoint in the poll plugin lacked post visibility checks which allowed unauthorized access to voters details of polls in any post. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.

Frequently asked questions

What is CVE-2026-27021?: Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, the voters endpoint in the poll plugin lacked post visibility checks which allowed unauthorized access to voters details of polls in any post. Versions 2025.12.2, 2026.1.1, and 2026.2.0 patch the issue. No known workarounds are available.
How severe is CVE-2026-27021?: CVE-2026-27021 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 low, integrity none, and availability none.
Is CVE-2026-27021 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27021?: CVE-2026-27021 primarily affects Discourse. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-27021?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-27021 have an EU (EUVD) identifier?: Yes. CVE-2026-27021 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8887.
When was CVE-2026-27021 published?: CVE-2026-27021 was published on 2026-02-26 and last updated on 2026-06-17.

References

https://github.com/discourse/discourse/security/advisories/GHSA-f5m5-9hpw-7c2g

Affected products (2)

cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*
cpe:2.3:a:discourse:discourse:2026.2.0:*:*:*:latest:*:*:*

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