EUVD-2026-281036

fkie_cve-2026-34148

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to 1.9.6, 1.10.5, 2.0.8, and 2.1.1, @fedify/fedify follows HTTP redirects recursively in its remote document loader and authenticated document loader without enforcing a maximum redirect count or visited-URL loop detection. An attacker who controls a remote ActivityPub key or actor URL can force a server using Fedify to make repeated outbound requests from a single inbound request, leading to resource consumption and denial of service. This vulnerability is fixed in 1.9.6, 1.10.5, 2.0.8, and 2.1.1.

GHSA-gm9m-gwc4-hwgp — Fedify affected by resource exhaustion caused by unbounded redirect following during remote key/document resolution

Affected: npm: @fedify/fedify, npm: @fedify/vocab-runtime

### Summary

`@fedify/fedify` follows HTTP redirects recursively in its remote document loader and authenticated document loader without enforcing a maximum redirect count or visited-URL loop detection. An attacker who controls a remote ActivityPub key or actor URL can force a server using Fedify to make repeated outbound requests from a single inbound request, leading to resource consumption and denial of service.

### Details

Fedify verifies ActivityPub HTTP signatures by fetching the remote `keyId` during request processing. The relevant flow is `handleInboxInternal()` -> `verifyRequest()` -> `fetchKeyInternal()` -> document loader.

In affected versions: - the generic document loader recursively follows `3xx` responses by calling `load()` again on the `Location` header - the authenticated redirect path (`doubleKnock()`) also recursively follows redirects - neither path enforces a redirect cap or tracks visited URLs to detect self-referential redirect loops

As a result, if an attacker-controlled `keyId` or actor URL responds with `302 Location: <same URL>`, a single ActivityPub request can trigger tens or hundreds of outbound requests before the fetch completes or the request times out.

I confirmed the issue in `@fedify/fedify` 1.9.1 and 1.9.2. By contrast, Fedify's WebFinger lookup path already has a redirect cap, which suggests the missing bound in the document loader is unintended.

Failed key fetches are not durably negatively cached. After a failed lookup, the nul…

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EUVD-2026-281036

fkie_cve-2026-34148

GHSA-gm9m-gwc4-hwgp — Fedify affected by resource exhaustion caused by unbounded redirect following during remote key/document resolution