How severe is CVE-2025-23221?

CVE-2025-23221 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.

Is CVE-2025-23221 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-23221?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-23221 have an EU (EUVD) identifier?

Yes. CVE-2025-23221 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-0153.

When was CVE-2025-23221 published?

CVE-2025-23221 was published on 2025-01-20 and last updated on 2026-06-17.

CVE-2025-23221

CVE-2025-23221 is a medium-severity vulnerability with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-0153
Weakness: CWE-835
Published: 2025-01-20
Last modified: 2026-06-17

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.

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 3.x base score of 5.4, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.
Is CVE-2025-23221 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-23221?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-23221 have an EU (EUVD) identifier?: Yes. CVE-2025-23221 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-0153.
When was CVE-2025-23221 published?: CVE-2025-23221 was published on 2025-01-20 and last updated on 2026-06-17.

References

Other CWE-835 (Loop with Unreachable Exit Condition (Infinite Loop)) vulnerabilities

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CVE-2017-12990 — Critical (CVSS 9.8): The ISAKMP parser in tcpdump before 4.9.2 could enter an infinite loop due to bugs in print-isakmp.c, several functions.
CVE-2026-31448 — Critical (CVSS 9.4): In the Linux kernel, the following vulnerability has been resolved: ext4: avoid infinite loops caused by residual…

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