CVE-2026-50131

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

HIGH

8.6

CVSS Score

Published: June 10, 2026 at 08:27 PM UTC

Updated: July 21, 2026 at 07:26 PM UTC

2 products affected across 1 vendorFedifyVocab Runtime

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Severity

HIGH8.6

Exploit prediction

EPSS 0.4%

SSVC

PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Fedify · Fedify Dev

60%

v < 1.10.11v < 1.9.12v < 2.0.19v < 2.1.15v < 2.2.4

Affected range stops below 1.10.11, so it looks safe — our inference, not a vendor statement

Affected range stops below 1.9.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.0.19, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.1.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.2.4, so it looks safe — our inference, not a vendor statement

Vocab Runtime · Fedify Dev

60%

v < 2.0.19v < 2.1.15v < 2.2.4

Affected range stops below 2.0.19, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.1.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.2.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

x_refsource_CONFIRM

Source: cverecord

https://github.com/fedify-dev/fedify/security/advisories/GHSA-xw9q-2mv6-9fr8

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHGitHub_M

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: LOW
Availability: LOW

Vector?

Quick Info

StatusDEFERRED

CWE

CWE-918CWE-1286CWE-1389

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