CVE-2026-55420
Discourse: Remote code execution via pdf uploads
8.1
HIGH
CVSS 3.1
EPSS 0.35%
Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
How to fix CVE-2026-55420
To remediate CVE-2026-55420, upgrade the affected package to a fixed version below.
- —upgrade to 2026.1.5 or later
Is CVE-2026-55420 being exploited?
Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 2026.1.0, < 2026.1.5, >= 2026.4.0, < 2026.4.2, >= 2026.5.0, < 2026.5.1, >= 2026.6.0, < 2026.7.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |