CVE-2026-50131
HighCVSS 8.6Exploitation Probability (EPSS)
Low risk19th percentile - higher than 19% of all known CVEs
Summary
Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Fedify previously addressed SSRF/internal network access in GHSA-p9cg-vqcc-grcx by adding public URL validation before runtime document and media fetching. However, the IPv4 validation logic present starting in version 0.11.2 and prior to versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 appears incomplete. The `validatePublicUrl()` protection relies on `isValidPublicIPv4Address()` to reject non-public IPv4 destinations. The function blocks common private and local ranges such as `10.0.0.0/8`, `127.0.0.0/8`, `169.254.0.0/16`, `172.16.0.0/12`, and `192.168.0.0/16`, but it still treats several special-use, reserved, multicast, benchmarking, and carrier-grade NAT IPv4 ranges as valid public destinations. Because this validation is used as an SSRF defense before outbound fetches, this appears to be an incomplete mitigation or bypass class for the previous SSRF issue. Versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 contain an updated patch.
Risk Assessment
The risk is potential SSRF attacks, which could allow access to internal network resources that should not be externally accessible.
Recommendation
Upgrade Fedify to one of the patched versions: 1.9.12, 1.10.11, 2.0.19, 2.1.15, or 2.2.4.
Other vulnerabilities in Fedify
See all- CVE-2026-62857High
Fedify from version 1.2.0 through affected 1.9, 1.10, 2.0, 2.1, 2.2, and 2.3 maintenance lines, in getNodeInfo(), follows an attacker-controlled links[].href value from /.well-known/nodeinfo without scheme, redirect, or private-address validation, allowing requests to loopback, link-local, cloud metadata, and private-network services and returning their response bodies. The issue is fixed in versions 1.9.13, 1.10.12, 2.0.22, 2.1.18, 2.2.7, and 2.3.2.
- CVE-2026-42462High
Fedify, a TypeScript library for building federated server apps with ActivityPub, is vulnerable to an attack exploiting JSON-LD features. An attacker can restructure a JSON-LD document without changing its Linked Data Signature, allowing modification of a third-party signed activity.
Original NVD description (English source)
Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Fedify previously addressed SSRF/internal network access in GHSA-p9cg-vqcc-grcx by adding public URL validation before runtime document and media fetching. However, the IPv4 validation logic present starting in version 0.11.2 and prior to versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 appears incomplete. The `validatePublicUrl()` protection relies on `isValidPublicIPv4Address()` to reject non-public IPv4 destinations. The function blocks common private and local ranges such as `10.0.0.0/8`, `127.0.0.0/8`, `169.254.0.0/16`, `172.16.0.0/12`, and `192.168.0.0/16`, but it still treats several special-use, reserved, multicast, benchmarking, and carrier-grade NAT IPv4 ranges as valid public destinations. Because this validation is used as an SSRF defense before outbound fetches, this appears to be an incomplete mitigation or bypass class for the previous SSRF issue. Versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 contain an updated patch.