fedify-dev fedify/vocab-runtime prior 1.9.12/1.10.11/2.0.19/2.1.15/2.2.4 URL Validation validatePublicUrl server-side request forgery

Summaryinfo

A vulnerability identified as critical has been detected in fedify-dev fedify and vocab-runtime. Affected by this vulnerability is the function validatePublicUrl of the component URL Validation Handler. The manipulation leads to server-side request forgery. This vulnerability is uniquely identified as CVE-2026-50131. The attack is possible to be carried out remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in fedify-dev fedify and vocab-runtime and classified as critical. This issue affects the function validatePublicUrl of the component URL Validation Handler. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-50131 since 06/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 1.9.12, 1.10.11, 2.0.19, 2.1.15 or 2.2.4 eliminates this vulnerability.

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Productinfo

Vendor

• fedify-dev

Name

• fedify
• vocab-runtime

Website

• Product: https://github.com/fedify-dev/fedify/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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