CVE-2026-33355
Received Received - Intake
Information Disclosure in Discourse /private-posts Endpoint via Visibility Bypass

Publication date: 2026-03-19

Last updated on: 2026-03-24

Assigner: GitHub, Inc.

Description
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the `/private-posts` endpoint did not apply post-type visibility filtering, allowing regular PM participants to see whisper posts in PM topics they had access to. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.
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Meta Information
Published
2026-03-19
Last Modified
2026-03-24
Generated
2026-06-16
AI Q&A
2026-03-20
EPSS Evaluated
2026-06-15
NVD
CVE-2026-33355
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
discourse discourse From 2026.1.0 (inc) to 2026.1.2 (exc)
discourse discourse From 2026.2.0 (inc) to 2026.2.1 (exc)
discourse discourse 2026.3.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
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Executive Summary

This vulnerability exists in the Discourse open-source discussion platform prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2. The issue is that the `/private-posts` endpoint did not properly apply post-type visibility filtering. As a result, regular private message (PM) participants could see whisper posts within PM topics they had access to, even though those whisper posts were intended to be hidden.

Impact Analysis

The impact of this vulnerability is that unauthorized users who are regular participants in private message topics could view sensitive whisper posts that were meant to be hidden. This leads to a confidentiality breach where private or sensitive information could be exposed to unintended recipients.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, you should upgrade your Discourse installation to one of the patched versions: 2026.3.0-latest.1, 2026.2.1, or 2026.1.2.

No known workarounds are available, so applying the patch by upgrading is the recommended immediate step.

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