How severe is CVE-2026-2880?

CVE-2026-2880 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-2880 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-2880?

CVE-2026-2880 affects Fastify Fastify/middie. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-2880?

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

Does CVE-2026-2880 have an EU (EUVD) identifier?

Yes. CVE-2026-2880 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9049.

When was CVE-2026-2880 published?

CVE-2026-2880 was published on 2026-02-27 and last updated on 2026-06-17.

CVE-2026-2880

CVE-2026-2880 is a critical-severity vulnerability in Fastify Fastify/middie with a CVSS 3.x base score of 9.1. 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-20.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 8.2
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-9049
Weakness: CWE-20
Affected product: Fastify Fastify/middie
Published: 2026-02-27
Last modified: 2026-06-17

Description

A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)). When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.

Frequently asked questions

What is CVE-2026-2880?: A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)). When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.
How severe is CVE-2026-2880?: CVE-2026-2880 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-2880 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-2880?: CVE-2026-2880 affects Fastify Fastify/middie. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-2880?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-2880 have an EU (EUVD) identifier?: Yes. CVE-2026-2880 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9049.
When was CVE-2026-2880 published?: CVE-2026-2880 was published on 2026-02-27 and last updated on 2026-06-17.

References

https://github.com/fastify/middie/security/advisories/GHSA-8p85-9qpw-fwgw

Affected products (1)

cpe:2.3:a:fastify:fastify\/middie:*:*:*:*:*:node.js:*:*

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