How severe is CVE-2026-25223?

CVE-2026-25223 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-25223 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25223?

CVE-2026-25223 affects Fastify. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25223?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-25223 have an EU (EUVD) identifier?

Yes. CVE-2026-25223 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5157.

When was CVE-2026-25223 published?

CVE-2026-25223 was published on 2026-02-03 and last updated on 2026-06-30.

CVE-2026-25223

CVE-2026-25223 is a high-severity vulnerability in Fastify with a CVSS 3.x base score of 7.5. 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-436.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5157
Weakness: CWE-436
Affected product: Fastify
Published: 2026-02-03
Last modified: 2026-06-30

Description

Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. This issue has been patched in version 5.7.2.

Frequently asked questions

What is CVE-2026-25223?: Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. This issue has been patched in version 5.7.2.
How severe is CVE-2026-25223?: CVE-2026-25223 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-25223 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25223?: CVE-2026-25223 affects Fastify. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25223?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-25223 have an EU (EUVD) identifier?: Yes. CVE-2026-25223 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5157.
When was CVE-2026-25223 published?: CVE-2026-25223 was published on 2026-02-03 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:*

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