CVE-2022-23549: Discourse vulnerable to bypass of post max_length using HTML comments

Severity: medium (CVSS 6.5 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: 2023-01-05 · updated 2026-06-17
Weakness: CWE-20

Description

Discourse is an option source discussion platform. Prior to version 2.8.14 on the `stable` branch and version 2.9.0.beta16 on the `beta` and `tests-passed` branches, users can create posts with raw body longer than the `max_length` site setting by including html comments that are not counted toward the character limit. This issue is patched in versions 2.8.14 and 2.9.0.beta16. There are no known workarounds.

Affected products

discourse: before 2.8.14; 2.9.0-beta1, 2.9.0-beta10, 2.9.0-beta11, 2.9.0-beta12, 2.9.0-beta13, 2.9.0-beta14 (+8) — fixed in 2.8.14

How to fix

Upgrade to a fixed version: discourse 2.8.14. Check the vendor advisory for mitigations.

References

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