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TI-2025-34361 Aliases CVE-2025-54590GHSA-8xq3-w9fx-74rv

webfinger.js is vulnerable to Blind SSRF attacks through localhost

Priority HIGH 70CWE-918Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-918 and the CVSS impact.

Summary

webfinger.js is a TypeScript-based WebFinger client that runs in both browsers and Node.js environments. In versions 2.8.0 and below, the lookup function accepts user addresses for account checking. However, the ActivityPub specification requires preventing access to localhost services in production. This library does not prevent localhost access, only checking for hosts that start with "localhost" and end with a port. Users can exploit this by creating servers that send GET requests with controlled host, path, and port parameters to query services on the instance's host or local network, enabling blind SSRF attacks. This is fixed in version 2.8.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00712 53rd percentileScored 2026-11-07
Fix Fixed webfinger.js (silverbucket): 2.8.1webfinger.js (npm): 2.8.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
silverbucketwebfinger.jsbefore 2.8.12.8.1Patch availableCNA
—webfinger.js (npm)before 2.8.12.8.1Patch availableGHSA-8xq3-w9fx-74rv
  • webfinger.js Vendorsilverbucket Affected before 2.8.1 Fixed in 2.8.1 Patch available CNA
  • webfinger.js (npm) Vendor— Affected before 2.8.1 Fixed in 2.8.1 Patch available GHSA-8xq3-w9fx-74rv

Remediation

  • Fix · CNA webfinger.js (silverbucket) Fixed in 2.8.1
  • Fix · GHSA-8xq3-w9fx-74rv webfinger.js (npm) Fixed in 2.8.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-54590
  2. 2026-10-03 Alias added: GHSA-8xq3-w9fx-74rv
  3. 2026-10-23 EPSS moved to the 50th–90th percentile

References

Advisory 1

Other 4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences