CVE-2023-28112: Discourse's SSRF protection missing for some FastImage requests

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-03-17 · updated 2026-06-17
Weakness: CWE-918

Description

Discourse is an open-source discussion platform. Prior to version 3.1.0.beta3 of the `beta` and `tests-passed` branches, some user provided URLs were being passed to FastImage without SSRF protection. Insufficient protections could enable attackers to trigger outbound network connections from the Discourse server to private IP addresses. This affects any site running the `tests-passed` or `beta` branches versions 3.1.0.beta2 and prior. This issue is patched in version 3.1.0.beta3 of the `beta` and `tests-passed` branches. There are no known workarounds.

Affected products

discourse: before 3.1.0; through 3.1.0; 3.1.0-beta1, 3.1.0-beta2 — fixed in 3.1.0

How to fix

Upgrade to a fixed version: discourse 3.1.0. Check the vendor advisory for mitigations.

References

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