CVE-2021-41140: Reactions leak for secure category topics and private messages

Severity: medium (CVSS 5.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-10-19 · updated 2026-06-17
Weakness: CWE-668

Description

Discourse-reactions is a plugin for the Discourse platform that allows user to add their reactions to the post. In affected versions reactions given by user to secure topics and private messages are visible. This issue is patched in version 0.2 of discourse-reaction. Users who are unable to update are advised to disable the Discourse-reactions plugin in admin panel.

Affected products

discourse-reactions: before 0.2 — fixed in 0.2

How to fix

Upgrade to a fixed version: discourse-reactions 0.2. Check the vendor advisory for mitigations.

References

https://github.com/discourse/discourse-reactions/commit/213d90b82fd15c4186ebc290fee18817d9727d0d
https://github.com/discourse/discourse-reactions/security/advisories/GHSA-9358-hwg5-jrmh
https://github.com/discourse/discourse-reactions/commit/213d90b82fd15c4186ebc290fee18817d9727d0d
https://github.com/discourse/discourse-reactions/security/advisories/GHSA-9358-hwg5-jrmh

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