CVE-2026-54286

Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)

Published Jun 22, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed
Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on Windows hosts, an encoded backslash (%5C) in the request path decodes to \, which the Windows path resolver treats as a separator. serve-static then resolves a single URL segment such as admin\secret.txt into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. This vulnerability is fixed in 4.12.25.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-wwfh-h76j-fc44 hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)
History
Type Values Removed Values Added
First Time appeared Hono
Hono hono
Vendors & Products Hono
Hono hono
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on Windows hosts, an encoded backslash (%5C) in the request path decodes to \, which the Windows path resolver treats as a separator. serve-static then resolves a single URL segment such as admin\secret.txt into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. This vulnerability is fixed in 4.12.25.
Title Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 23, 2026, 2:07 PM
Reserved
Jun 12, 2026, 5:46 PM
Status
Deferred
Published
Jun 22, 2026, 6:16 PM
Modified
Oct 25, 2026, 11:10 PM