What’s Vulnerable › Vulnerabilities

CVE-2025-23221: Fedify has an Infinite loop and Blind SSRF found inside the Webfinger mechanism

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-01-20 · updated 2026-06-17
• Weakness: CWE-835

Description

Fedify is a TypeScript library for building federated server apps powered by ActivityPub and other standards. This vulnerability allows a user to maneuver the Webfinger mechanism to perform a GET request to any internal resource on any Host, Port, URL combination regardless of present security mechanisms, and forcing the victim’s server into an infinite loop causing Denial of Service. Moreover, this issue can also be maneuvered into performing a Blind SSRF attack. This vulnerability is fixed in 1.0.14, 1.1.11, 1.2.11, and 1.3.4.

Affected products

• dahlia fedify: before 1.0.14; from 1.1.0, < 1.1.11; from 1.2.0, < 1.2.11; from 1.3.0, < 1.3.4

References

• https://github.com/dahlia/fedify/commit/8be3c2038eebf4ae12481683a1e809b314be3151
• https://github.com/dahlia/fedify/commit/c505eb82fcd6b5b17174c6659c29721bc801ab9a
• https://github.com/dahlia/fedify/commit/e921134dd5097586e4563ea80b9e8d1b5460a645
• https://github.com/dahlia/fedify/security/advisories/GHSA-c59p-wq67-24wx

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