CVE-2026-29045
Received Received - Intake
Inconsistent URL Decoding in Hono serveStatic Enables Unauthorized Access

Publication date: 2026-03-04

Last updated on: 2026-03-06

Assigner: GitHub, Inc.

Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using serveStatic together with route-based middleware protections (e.g. app.use('/admin/*', ...)), inconsistent URL decoding allowed protected static resources to be accessed without authorization. The router used decodeURI, while serveStatic used decodeURIComponent. This mismatch allowed paths containing encoded slashes (%2F) to bypass middleware protections while still resolving to the intended filesystem path. This issue has been patched in version 4.12.4.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2026-03-04
Last Modified
2026-03-06
Generated
2026-06-16
AI Q&A
2026-03-05
EPSS Evaluated
2026-06-15
NVD
CVE-2026-29045
EUVD
EUVD-2026-9506
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
hono hono to 4.12.4 (exc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-177 The product does not properly handle when all or part of an input has been URL encoded.
Attack-Flow Graph
AI Quick Actions
Instant insights powered by AI
Impact Analysis

This vulnerability can lead to unauthorized access to protected static resources within a web application using the Hono framework. Attackers can exploit the inconsistent URL decoding to bypass security controls and access sensitive files or data that should be restricted.

The CVSS score of 7.5 indicates a high severity impact, with the vulnerability being remotely exploitable without any privileges or user interaction, and it can result in high confidentiality impact.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade the Hono framework to version 4.12.4 or later, where the issue has been patched.

Executive Summary

This vulnerability exists in the Hono web application framework prior to version 4.12.4. It occurs because of inconsistent URL decoding between two components: the router and the serveStatic middleware. The router uses decodeURI while serveStatic uses decodeURIComponent. This mismatch allows attackers to use encoded slashes (%2F) in URLs to bypass route-based middleware protections that are meant to restrict access to certain static resources.

As a result, protected static resources can be accessed without proper authorization, even though middleware protections are in place.

Chat Assistant
Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-29045. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70
EPSS Chart