CVE-2026-55420

EUVD-2026-42665
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.
OS Command Injection
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
HIGH
LOW
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 27.98%
Affected Products (NVD)
VendorProductVersion
discoursediscourse
2026.1.0 ≤
𝑥
< 2026.1.5
discoursediscourse
2026.4.0 ≤
𝑥
< 2026.4.2
discoursediscourse
2026.5.0 ≤
𝑥
< 2026.5.1
discoursediscourse
2026.6.0
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://github.com/discourse/discourse/commit/ca5a7e06167561928556afa2f237d67e459c6914
https://github.com/discourse/discourse/releases/tag/v2026.1.5
https://github.com/discourse/discourse/releases/tag/v2026.4.2
https://github.com/discourse/discourse/releases/tag/v2026.5.1
https://github.com/discourse/discourse/releases/tag/v2026.6.0
https://github.com/discourse/discourse/security/advisories/GHSA-7wq5-jgww-5rw3