CVE-2026-107832

fastify is a fast and low overhead web framework for Node.js. In versions 5.12.2 through 5.12.5, the routine that lowercases header names declared in a route schema does not lowercase the enum or const header names nested inside a propertyNames subschema. As a result, a header allow-list or deny-list written with canonical (non-lowercase) casing never matches the incoming lowercased header, so a restricted header passes validation and reaches the route handler. An attacker can therefore bypass a case-sensitive header validation rule and smuggle a forbidden header past the schema, affecting the integrity of request handling. The issue is fixed in fastify 5.12.6, and users should upgrade to 5.12.6 or later. There is no workaround other than upgrading, though applications can declare header names in lowercase to avoid the mismatch.

CVSS v3 3.7 LOW

3.7^/10

CVSS v3 : LOW

Vector :

Exploitability : 2.2 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://cna.openjsf.org/security-advisories.html
https://github.com/fastify/fastify/security/advisories/GHSA-389g-gv7q-r4x8

Configurations

No configuration.

History

13 Oct 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-13 14:17

Updated : 2026-10-15 20:38

NVD link : CVE-2026-107832

Mitre link : CVE-2026-107832

CVE.ORG link : CVE-2026-107832

JSON object : View

Products Affected

No product.

CWE

CWE-178

Improper Handling of Case Sensitivity

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