What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-11-10 · updated 2026-06-17
• Weakness: CWE-770

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.

Affected products

• discourse: from 3.1.0 before 3.1.3; 3.1.0-beta6, 3.1.0-beta7, 3.1.0-beta8, 3.2.0-beta1, 3.2.0-beta2 — fixed in 3.1.3

How to fix

Upgrade to a fixed version: discourse 3.1.3. Check the vendor advisory for mitigations.

References

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

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