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CVE-2025-23221

MEDIUMCVSS 5.4/10EPSS 0.57%

Last modified

CVE-2025-23221 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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. EPSS estimates a 0.57% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5.4/10

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

EPSS Probability
0.57%

42.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2025-23221?
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.
How severe is CVE-2025-23221?
CVE-2025-23221 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.57% probability of exploitation in the next 30 days.
How do I fix CVE-2025-23221?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-23221?

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Source: NVD / NIST