CVE-2026-50131
Fedify has an incomplete SSRF mitigation after GHSA-p9cg-vqcc-grcx: validatePublicUrl allows special-use IPv4 ranges
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L |
| NVDNVD · Deferred | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L |
- EPSS (exploitation in 30 days)
- 0.35% · top 71% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.6.
Weakness
- CWE-918: Server-Side Request Forgery (SSRF) (opens in a new tab)All about CWE-918 and its CVEs
- CWE-1286: Improper Validation of Syntactic Correctness of Input (opens in a new tab)All about CWE-1286 and its CVEs
- CWE-1389: Incorrect Parsing of Numbers with Different Radices (opens in a new tab)All about CWE-1389 and its CVEs
Affected products
- affected >= 0.11.2, < 1.9.12
- affected >= 1.10.0, < 1.10.11
- affected >= 2.0.0, < 2.0.19
- affected >= 2.1.0, < 2.1.15
- affected >= 2.2.0, < 2.2.4
- affected < 2.0.19
- affected >= 2.1.0, < 2.1.15
- affected >= 2.2.0, < 2.2.4
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npm@fedify/fedifyGHSA-xw9q-2mv6-9fr8 (opens in a new tab)
- npm@fedify/vocab-runtimeGHSA-xw9q-2mv6-9fr8 (opens in a new tab)
References (1)
- https://github.com/fedify-dev/fedify/security/advisories/GHSA-xw9q-2mv6-9fr8 (opens in a new tab)x_refsource_CONFIRMexploit
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-xw9q-2mv6-9fr8 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-50131)Record last updated .