Executive Summary

[{'type': 'paragraph', 'content': 'This vulnerability exists in the Discourse open source discussion platform. It occurs because the "move_posts" action only checks if a user has permission to move posts from the source topic but does not verify if the user has write permissions on the destination topic.'}, {'type': 'paragraph', 'content': 'As a result, users with Trust Level 4 (TL4) and category group moderators can move posts into topics within categories where they normally lack posting privileges, such as read-only categories or categories with group-restricted write access.'}, {'type': 'paragraph', 'content': 'This is a missing authorization issue (CWE-862) where proper permission checks are not performed on the destination topic.'}] [1]

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Impact Analysis

[{'type': 'paragraph', 'content': 'This vulnerability can allow users who should not have posting rights in certain categories to move posts into those restricted areas.'}, {'type': 'paragraph', 'content': 'This could lead to unauthorized content being placed in read-only or restricted categories, potentially disrupting the intended access controls and content organization.'}, {'type': 'paragraph', 'content': "It may also undermine trust in the platform's permission system and could be exploited to bypass restrictions on posting."}] [1]

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Compliance Impact

I don't know

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Detection Guidance

There is no specific information provided about detection methods or commands to identify this vulnerability on your network or system.

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Mitigation Strategies

The recommended immediate step to mitigate this vulnerability is to upgrade Discourse to one of the patched versions: 2025.12.2, 2026.1.1, or 2026.2.0.

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