Incorrect Behavior Order

Overview @fastify/express is an Express compatibility layer for Fastify Affected versions of this package are vulnerable to Incorrect Behavior Order due to incorrect mount path prefix rewriting in the use middleware handling. An attacker can reach protected routes without the intended middleware ...

@bedrock/express (8.6.5), @cmmn/tools (>=3.0.0-alpha-1, <=3.0.0-alpha-6) +1 more potentially affected by CVE-2026-6556 via @fastify/express (>=4.0.1, <=4.0.5)

@fastify/express NPM version =4.0.1, =3.0.0-alpha-1, =3.0.0-alpha-6 - mikr0 0.1.10 Source cves: CVE-2026-6556 Source advisory: SNYK:JS-FASTIFYEXPRESS-17744444...

CVE-2026-6556

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

CVE-2026-6556 @fastify/express vulnerable to middleware bypass via non-string mount paths in prefixed plugins

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

EUVD-2026-40309

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

CVE-2026-6556 @fastify/express vulnerable to middleware bypass via non-string mount paths in prefixed plugins

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

CVE-2026-6556 @fastify/express vulnerable to middleware bypass via non-string mount paths in prefixed plugins

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

CVE-2026-6556

@fastify/express versions 4.0.6 and earlier only rewrite the plugin prefix for middleware mount paths when the path argument is a string. Non-string mount paths arrays of paths and regular expressions are left unprefixed inside prefixed plugin scopes, so middleware registered with those forms doe...

CVE-2026-6556

The CVE concerns @fastify/express 4.0.6 and earlier, where non-string mount paths (arrays/regex) are not prefixed inside prefixed plugin scopes. This causes middleware registered with those forms to not match the actual prefixed request path, potentially bypassing path-scoped security middleware ...

PT-2026-53878

Name of the Vulnerable Software and Affected Versions @fastify/express versions prior to 4.0.7 Description A middleware scoping flaw exists where plugin prefixes are not applied to middleware mount paths when the mount path is provided as an array or a regular expression. This occurs due to...

CVE-2026-33808

Impact@fastify/express v4.0.4 and earlier fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via duplicate slashes when ignoreDuplicateSlashes is enabled, or...

Improper Access Control

@fastify/express is vulnerable to Improper Access Control. The vulnerability is due to incorrect path handling in the onRegister function, where middleware paths are duplicated when inherited by child plugins, causing them to not match incoming requests and resulting in bypass of security control...

@cmmn/tools (>=3.0.0-alpha-1, <=3.0.0-alpha-6), mikr0 (0.1.10) potentially affected by CVE-2026-33808 via @fastify/express (>=4.0.1, <=4.0.2)

@fastify/express NPM version =4.0.1, =3.0.0-alpha-1, =3.0.0-alpha-6 - mikr0 0.1.10 Source cves: CVE-2026-33808 Source advisory: OSV:GHSA-6HW5-45GM-FJ88...

GHSA-6HW5-45GM-FJ88 @fastify/express has a middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

Summary @fastify/express v4.0.4 fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via two vectors: 1. Duplicate slashes //admin/dashboard when...

@fastify/express has a middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)

Summary @fastify/express v4.0.4 fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via two vectors: 1. Duplicate slashes //admin/dashboard when...

EUVD-2026-22881

@fastify/express has a middleware authentication bypass via URL normalization gaps duplicate slashes and semicolons...

@fastify/express's middleware path doubling causes authentication bypass in child plugin scopes

Summary @fastify/express v4.0.4 contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. This results in complete bypass of Express middleware security controls for all routes defined within child plugin scopes that share ...

@cmmn/tools (>=3.0.0-alpha-1, <=3.0.0-alpha-6), mikr0 (0.1.10) potentially affected by CVE-2026-33807 +1 more via @fastify/express (>=4.0.1, <=4.0.2)

@fastify/express NPM version =4.0.1, =3.0.0-alpha-1, =3.0.0-alpha-6 - mikr0 0.1.10 Source cves: CVE-2026-33807, CVE-2026-6270 Source advisory: OSV:GHSA-HRWM-HGMJ-7P9C...

EUVD-2026-22880

@fastify/express's middleware path doubling causes authentication bypass in child plugin scopes...

GHSA-HRWM-HGMJ-7P9C @fastify/express's middleware path doubling causes authentication bypass in child plugin scopes

Summary @fastify/express v4.0.4 contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. This results in complete bypass of Express middleware security controls for all routes defined within child plugin scopes that share ...