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Vulnerability · Published Jun 10, 2026 · Assigned by GitHub_M

CVE-2026-50131Fedify has an incomplete SSRF mitigation after GHSA-p9cg-vqcc-grcx: validatePublicUrl allows special-use IPv4 ranges

High 8.6

In plain English

A high-severity server-side request forgery in fedify from fedify-dev. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.6High
Exploit odds (30 days)0.4%top 71.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack tooling1Public PoC

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npm@fedify/fedify1.9.12GHSA-xw9q-2mv6-9fr8
npm@fedify/fedify1.10.11GHSA-xw9q-2mv6-9fr8
npm@fedify/fedify2.0.19GHSA-xw9q-2mv6-9fr8
npm@fedify/fedify2.1.15GHSA-xw9q-2mv6-9fr8
npm@fedify/fedify2.2.4GHSA-xw9q-2mv6-9fr8
npm@fedify/vocab-runtime2.0.19GHSA-xw9q-2mv6-9fr8
npm@fedify/vocab-runtime2.1.15GHSA-xw9q-2mv6-9fr8
npm@fedify/vocab-runtime2.2.4GHSA-xw9q-2mv6-9fr8

Affected products (as reported)

VendorProductVersions
fedify-dev fedify >= 0.11.2, < 1.9.12>= 1.10.0, < 1.10.11>= 2.0.0, < 2.0.19>= 2.1.0, < 2.1.15>= 2.2.0, < 2.2.4
fedify-dev vocab-runtime < 2.0.19>= 2.1.0, < 2.1.15>= 2.2.0, < 2.2.4

Weakness: CWE-918, CWE-1286, CWE-1389 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

References