@fedify/fedify: Improper Authentication and Incorrect Authorization

Summary

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. In versions below 1.3.20, 1.4.0-dev.585 through 1.4.12, 1.5.0-dev.636 through 1.5.4, 1.6.0-dev.754 through 1.6.7, 1.7.0-pr.251.885 through 1.7.8 and 1.8.0-dev.909 through 1.8.4, an authentication bypass vulnerability allows any unauthenticated attacker to impersonate any ActivityPub actor by sending forged activities signed with their own keys. Activities are processed before verifying the signing key belongs to the claimed actor, enabling complete actor impersonation across all Fedify instances. This is fixed in versions 1.3.20, 1.4.13, 1.5.5, 1.6.8, 1.7.9 and 1.8.5.

Timeline

1. Aug 9, 2025, 1:31 AM UTCCVE published
2. Aug 11, 2025, 1:48 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: yes · Technical impact: partial

3. Feb 4, 2026, 10:13 PM UTCRecord last updated

Affected versions

• fedify-dev fedify

  fixed in 1.3.20; From 1.4.0-dev.585 · fixed in 1.4.13; From 1.5.0-dev.636 · fixed in 1.5.5; From 1.6.0-dev.754 · fixed in 1.6.8; From 1.7.0-pr.251.885 · fixed in 1.7.9; From 1.8.0-dev.909 · fixed in 1.8.5

• @fedify/fedifynpm

  fixed in 1.3.20

• @fedify/fedifynpm

  From 1.4.0-dev.585 · fixed in 1.4.13

• @fedify/fedifynpm

  From 1.5.0-dev.636 · fixed in 1.5.5

• @fedify/fedifynpm

  From 1.6.0-dev.754 · fixed in 1.6.8

• @fedify/fedifynpm

  From 1.7.0-pr.251.885 · fixed in 1.7.9

• @fedify/fedifynpm

  From 1.8.0-dev.909 · fixed in 1.8.5

References 2