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CVE-2026-2880

Fastify Fastify/middie vulnerability

9.1 CRITICALEPSS 0.52%
  1. Published27 Feb 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Fastify Fastify/middie< 9.2.0

Remediation

Fixed in
Fastify Fastify/middie≥ 9.2.0

References

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Frequently asked

Is CVE-2026-2880 being actively exploited?

CVE-2026-2880 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.52%.

How severe is CVE-2026-2880?

CVE-2026-2880 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.52% probability of exploitation.

Which products are affected by CVE-2026-2880?

Affected products include Fastify Fastify/middie.

How do I fix CVE-2026-2880?

Upgrade affected software to a fixed version, for example Fastify Fastify/middie 9.2.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-2880 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.