CVE-2026-9495

Access Control Bypass in Koa Router Prefix Path Parameters

Published May 26, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-47p6-69vm-vw6v @koa/router has an Access Control Bypass
History
Type Values Removed Values Added
First Time appeared Koajs
Koajs router
Vendors & Products Koajs
Koajs router
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
snyk
Published
Updated
May 26, 2026, 12:41 PM
Reserved
May 25, 2026, 9:18 AM
Status
Awaiting Analysis
Published
May 26, 2026, 7:16 AM
Modified
Jul 23, 2026, 11:10 AM