What’s Vulnerable › Vulnerabilities

CVE-2025-54590: webfinger.js is vulnerable to Blind SSRF attacks through localhost

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-01 · updated 2026-06-17
• Weakness: CWE-918

Description

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.

Affected products

• silverbucket webfinger.js: before 2.8.1

References

• https://github.com/silverbucket/webfinger.js/commit/b5f2f2c957297d25f4d76072963fccaee2e3095a
• https://github.com/silverbucket/webfinger.js/releases/tag/v2.8.1
• https://github.com/silverbucket/webfinger.js/security/advisories/GHSA-8xq3-w9fx-74rv

Get alerted when CVE-2025-54590 or the next vulnerability affects your stack