@fedify/fedify: Improper Authentication and Incorrect Authorization

published 2025-08-08 15 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-24039 , GHSA-6jcc-xgcr-q3h4

cvss: 8.7; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 51%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

npm @fedify/fedify 1.3.20, 1.4.13, 1.5.5, 1.6.8, 1.7.9, 1.8.5
fedify fedify 1.3.20, 1.4.13, 1.5.5, 1.6.8, 1.7.9, 1.8.5

github.com/fedify-dev/fedify@14a2f8c commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 14 mo ago (2025-08-11)

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA	4.0	8.7	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem	package	affected	fixed in
npm	@fedify/fedify	<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	1.3.20 1.4.13 1.5.5 1.6.8 1.7.9 1.8.5

Affected products

fedify-dev fedify

Classification

Weakness

CWE-287 Improper Authentication
CWE-863 Incorrect Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary