How severe is CVE-2026-6414?

CVE-2026-6414 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-6414 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6414?

CVE-2026-6414 affects Fastify Fastify-static. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6414?

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

Does CVE-2026-6414 have an EU (EUVD) identifier?

Yes. CVE-2026-6414 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23227.

When was CVE-2026-6414 published?

CVE-2026-6414 was published on 2026-04-16 and last updated on 2026-06-17.

CVE-2026-6414

CVE-2026-6414 is a medium-severity vulnerability in Fastify Fastify-static with a CVSS 3.x base score of 5.9. 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-177.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23227
Weakness: CWE-177
Affected product: Fastify Fastify-static
Published: 2026-04-16
Last modified: 2026-06-17

Description

@fastify/static versions 8.0.0 through 9.1.0 decode percent-encoded path separators (%2F) before filesystem resolution, while Fastify's router treats them as literal characters. This mismatch allows attackers to bypass route-based middleware or guards that protect files served by @fastify/static. For example, a route guard on a protected path can be circumvented by encoding the path separator in the URL. Upgrade to @fastify/static 9.1.1 to fix this issue. There are no workarounds.

Frequently asked questions

What is CVE-2026-6414?: @fastify/static versions 8.0.0 through 9.1.0 decode percent-encoded path separators (%2F) before filesystem resolution, while Fastify's router treats them as literal characters. This mismatch allows attackers to bypass route-based middleware or guards that protect files served by @fastify/static. For example, a route guard on a protected path can be circumvented by encoding the path separator in the URL. Upgrade to @fastify/static 9.1.1 to fix this issue. There are no workarounds.
How severe is CVE-2026-6414?: CVE-2026-6414 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-6414 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6414?: CVE-2026-6414 affects Fastify Fastify-static. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6414?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6414 have an EU (EUVD) identifier?: Yes. CVE-2026-6414 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23227.
When was CVE-2026-6414 published?: CVE-2026-6414 was published on 2026-04-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:fastify:fastify-static:*:*:*:*:*:*:*:*

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