High severity · published Jul 9, 2026
CVE-2026-55420
Discourse: Remote code execution via pdf uploads
8.1
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 49% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
discourse · discourse
>= 2026.5.0-latest, < 2026.5.1; >= 2026.4.0-latest, < 2026.4.2; >= 2026.1.0-latest, < 2026.1.5 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55420
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55420
Patch
https://github.com/discourse/discourse/commit/ca5a7e06167561928556afa2f237d67e459c6914
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.1.5
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.4.2
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.5.1
Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.6.0
Mitigation
https://github.com/discourse/discourse/security/advisories/GHSA-7wq5-jgww-5rw3
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