Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2, a Regular Expression Denial of Service (ReDoS) vulnerability exists in Fedifys document loader. The HTML parsing regex at packages/fedify/src/runtime/docloader.ts:259 contains nested quantifiers that cause catastrophic backtracking when processing maliciously crafted HTML responses. This issue has been patched in versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2.
Weakness
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Fedify | Fedify | * | 1.6.13 (excluding) |
| Fedify | Fedify | 1.7.0 (including) | 1.7.14 (excluding) |
| Fedify | Fedify | 1.8.1 (including) | 1.8.15 (excluding) |
| Fedify | Fedify | 1.9.0 (including) | 1.9.2 (excluding) |
Extended Description
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.
Potential Mitigations
Related Attack Patterns
References
- https://github.com/fedify-dev/fedify/commit/2bdcb24d7d6d5886e0214ed504b63a6dc5488779
- https://github.com/fedify-dev/fedify/commit/bf2f0783634efed2663d1b187dc55461ee1f987a
- https://github.com/fedify-dev/fedify/releases/tag/1.6.13
- https://github.com/fedify-dev/fedify/releases/tag/1.7.14
- https://github.com/fedify-dev/fedify/releases/tag/1.8.15
- https://github.com/fedify-dev/fedify/releases/tag/1.9.2
- https://github.com/fedify-dev/fedify/security/advisories/GHSA-rchf-xwx2-hm93