Auth bypass in Fedify-Dev Fedify
CVE-2025-54888
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.
Vulnerability class: Broken Authentication
EPSS: 0.006 (47.9th percentile) — read the EPSS interpretation.
Affected products
- Fedify-dev Fedify — versions < 1.3.20, >= 1.4.0-dev.585, < 1.4.13, >= 1.5.0-dev.636, < 1.5.5
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2025-54888?
- CVE-2025-54888 is a vulnerability in Fedify-Dev Fedify, classified under Improper Authentication. Published 2025-08-09.
- Is CVE-2025-54888 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.