CVE-2026-50131: Fedify SSRF via incomplete IPv4 validation in validatePublicUrl

CVE-2026-50131 · Severity: high · CVSS 8.6 · Published 2026-06-10

Fedify, a library for building decentralized social media applications, contains a flaw in how it validates web addresses. While it attempts to block access to private internal networks, it fails to recognize several special-use and reserved address ranges as restricted. An attacker could exploit this to force the server to send requests to internal or sensitive network locations, potentially leading to unauthorized data access or service disruption.

Technologies: Fedify, @fedify/fedify (npm). Vendors: Fedify, npm.

Quick answers

Is CVE-2026-50131 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-50131 being exploited in the wild.
How severe is CVE-2026-50131?
High severity, with a CVSS score of 8.6, published 10 June 2026.
Which products and versions are affected?
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 Vocab Runtime < 2.0.19; >= 2.1.0, < 2.1.15; >= 2.2.0, < 2.2.4; @fedify/fedify (npm) SEMVER:introduced=0.11.2,fixed=1.9.12; @fedify/vocab-runtime (npm) SEMVER:introduced=0,fixed=2.0.19.
Is there a fix for CVE-2026-50131?
Yes. @fedify/fedify (npm): upgrade to 1.9.12 or later; @fedify/vocab-runtime (npm): upgrade to 2.0.19 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-50131 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-50131?
Check whether you run Fedify, Fedify Vocab Runtime, @fedify/fedify (npm) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • @fedify/fedify (npm): upgrade to 1.9.12 or later
    npm install @fedify/fedify@1.9.12
  • @fedify/vocab-runtime (npm): upgrade to 2.0.19 or later
    npm install @fedify/vocab-runtime@2.0.19

Technical details

The vulnerability exists in the `isValidPublicIPv4Address` function within `packages/vocab-runtime/src/url.ts`. While the function implements a denylist for common private ranges (like 10.0.0.0/8 and 192.168.0.0/16), it fails to account for other non-public ranges including Carrier-grade NAT (100.64.0.0/10), Benchmarking (198.18.0.0/15), Multicast (224.0.0.0/4), and IETF protocol assignments (192.0.0.0/24). An attacker can provide a specially crafted ActivityPub object or media URL pointing to these ranges to bypass SSRF protections. The issue is fixed in versions 1.9.12, 1.10.11, 2.0.19, 2.1.15, and 2.2.4 by expanding the validation logic to cover all IANA special-use IPv4 ranges.

Affected products

  • 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

Identifiers

  • CVE-2026-50131
  • GHSA-xw9q-2mv6-9fr8

Timeline

  • 2026-06-08: advisory: Initial advisory published
  • 2026-07-14: advisory: Advisory updated

References

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