TI-2026-39186 Aliases CVE-2026-54286 GHSA-wwfh-h76j-fc44

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

LOW 27CWE-22Published 2026-06-22 · Updated 2026-06-23

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Information disclosure
Confidentiality · integrity · availability: High · None · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00433 37th percentileScored 2026-11-07

Fix Fixed hono (honojs): 4.12.25hono (npm): 4.12.25

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
honojs	hono	before 4.12.25	4.12.25	Patch available	CNA
—	hono (npm)	before 4.12.25	4.12.25	Patch available	GHSA-wwfh-h76j-fc44

hono Vendorhonojs Affected before 4.12.25 Fixed in 4.12.25 Patch available CNA
hono (npm) Vendor— Affected before 4.12.25 Fixed in 4.12.25 Patch available GHSA-wwfh-h76j-fc44

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:hono:hono::::::::	—	—	honojs

cpe:2.3:a:hono:hono:*:*:*:*:*:*:*:* Versions — — ·honojs

Remediation

Fix · CNA hono (honojs) Fixed in 4.12.25
Fix · GHSA-wwfh-h76j-fc44 hono (npm) Fixed in 4.12.25 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-54286
2026-10-03 Alias added: GHSA-wwfh-h76j-fc44

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-54286

Other 2

TI-2024-21741 Hono vulnerable to Restricted Directory Traversal in serveStatic with deno CVSS 3.1MEDIUM 5.3
TI-2024-15441 @hono/node-server can't handle "double dots" in URL CVSS 3.1MEDIUM 5.3
TI-2024-32610 Hono vulnerable to bypass of CSRF Middleware by a request without Content-Type header. CVSS 3.1MEDIUM 5.9
TI-2024-29381 Hono CSRF middleware can be bypassed using crafted Content-Type header CVSS 3.1MEDIUM 5.0
TI-2026-39189 Hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest CVSS 3.1MEDIUM 4.8
TI-2026-23190 Hono: Arbitrary file access via serveStatic vulnerability CVSS 3.1CRITICAL 9.8

See all 59 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences