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, parsing posts can be susceptible to regular expression denial of service (ReDoS) attacks. This issue is patched in versions 2.8.14 and 2.9.0.beta16. There are no known workarounds.
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Discourse | Discourse | * | 2.8.14 (excluding) |
| Discourse | Discourse | 2.9.0-beta1 (including) | 2.9.0-beta1 (including) |
| Discourse | Discourse | 2.9.0-beta10 (including) | 2.9.0-beta10 (including) |
| Discourse | Discourse | 2.9.0-beta11 (including) | 2.9.0-beta11 (including) |
| Discourse | Discourse | 2.9.0-beta12 (including) | 2.9.0-beta12 (including) |
| Discourse | Discourse | 2.9.0-beta13 (including) | 2.9.0-beta13 (including) |
| Discourse | Discourse | 2.9.0-beta14 (including) | 2.9.0-beta14 (including) |
| Discourse | Discourse | 2.9.0-beta2 (including) | 2.9.0-beta2 (including) |
| Discourse | Discourse | 2.9.0-beta3 (including) | 2.9.0-beta3 (including) |
| Discourse | Discourse | 2.9.0-beta4 (including) | 2.9.0-beta4 (including) |
| Discourse | Discourse | 2.9.0-beta5 (including) | 2.9.0-beta5 (including) |
| Discourse | Discourse | 2.9.0-beta6 (including) | 2.9.0-beta6 (including) |
| Discourse | Discourse | 2.9.0-beta7 (including) | 2.9.0-beta7 (including) |
| Discourse | Discourse | 2.9.0-beta8 (including) | 2.9.0-beta8 (including) |
| Discourse | Discourse | 3.0.0-beta15 (including) | 3.0.0-beta15 (including) |
Attackers can create crafted inputs that
intentionally cause the regular expression to use
excessive backtracking in a way that causes the CPU
consumption to spike.