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

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Summary

CVECVE-2026-50131
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-10 22:17:01 UTC
Updated2026-06-11 16:16:24 UTC
DescriptionFedify 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 And Classification

Primary CVSS: v3.1 8.6 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

Problem Types: CWE-918 | CWE-1286 | CWE-1389 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF) | CWE-1286 CWE-1286: Improper Validation of Syntactic Correctness of Input | CWE-1389 CWE-1389: Incorrect Parsing of Numbers with Different Radices

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
3.1CNADECLARED8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Fedify-dev Fedify affected >= 0.11.2, < 1.9.12 Not specified
CNA Fedify-dev Fedify affected >= 1.10.0, < 1.10.11 Not specified
CNA Fedify-dev Fedify affected >= 2.0.0, < 2.0.19 Not specified
CNA Fedify-dev Fedify affected >= 2.1.0, < 2.1.15 Not specified
CNA Fedify-dev Fedify affected >= 2.2.0, < 2.2.4 Not specified
CNA Fedify-dev Vocab-runtime affected < 2.0.19 Not specified
CNA Fedify-dev Vocab-runtime affected >= 2.1.0, < 2.1.15 Not specified
CNA Fedify-dev Vocab-runtime affected >= 2.2.0, < 2.2.4 Not specified

References

ReferenceSourceLinkTags
github.com/fedify-dev/fedify/security/advisories/GHSA-xw9q-2mv6-9fr8 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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