CVE-2023-28440: Denial of service via admin theme import route in Discourse

Severity: low (CVSS 2.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-04-18 · updated 2026-06-17
Weakness: CWE-400

Description

Discourse is an open source platform for community discussion. In affected versions a maliciously crafted request from a Discourse administrator can lead to a long-running request and eventual timeout. This has the greatest potential impact in shared hosting environments where admins are untrusted. This issue has been addressed in versions 3.0.3 and 3.1.0.beta4. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Affected products

discourse: before 3.0.3; 1.1.0-beta1, 1.1.0-beta2, 1.1.0-beta3, 1.1.0-beta4, 1.1.0-beta5, 1.1.0-beta6 (+203) — fixed in 3.0.3

How to fix

Upgrade to a fixed version: discourse 3.0.3. Check the vendor advisory for mitigations.

References

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