Versions of the package @koa/router from 14.0.0 and before 15.0.0 are vulnerable to Access Control Bypass due to the middleware being silently dropped from the execution chain when the router prefix contains path parameters. Depending on what the skipped middleware was supposed to protect, an attacker could bypass authentication and authorization, evade rate limiting or bypass input sanitization.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
n/a @koa/router affected
Version Status Constraints
14.0.0 affected < 15.0.0

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Project Subscriptions

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/koajs/router/commit/d53e17f284557b1f417946f9807ee52290c3c759 cve-icon
https://github.com/koajs/router/issues/202 cve-icon
https://github.com/koajs/router/pull/206 cve-icon
https://security.snyk.io/vuln/SNYK-JS-KOAROUTER-12215044 cve-icon
History

Tue, 26 May 2026 07:45:00 +0000

Type Values Removed Values Added
Title Access Control Bypass in Koa Router Prefix Path Parameters

Tue, 26 May 2026 06:30:00 +0000

Type Values Removed Values Added
Description Versions of the package @koa/router from 14.0.0 and before 15.0.0 are vulnerable to Access Control Bypass due to the middleware being silently dropped from the execution chain when the router prefix contains path parameters. Depending on what the skipped middleware was supposed to protect, an attacker could bypass authentication and authorization, evade rate limiting or bypass input sanitization.
Weaknesses CWE-284
References
Metrics cvssV3_1

{'score': 7.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: snyk

Published:

Updated: 2026-05-26T05:00:04.704Z

Reserved: 2026-05-25T09:18:41.020Z

Link: CVE-2026-9495

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-26T07:30:36Z

Weaknesses