TI-2026-42709 Aliases CVE-2026-59895 GHSA-w62v-xxxg-mg59

Hono: Server-Side XSS via JSX Escaping Bypass in cx() Utility

LOW 27CWE-116Published 2026-07-08 · Updated 2026-07-08

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Cross-site scripting
Confidentiality · integrity · availability: Low · Low · None
Fix status: Partial Red Hat: 4 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-79.

Summary

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.0.0 before 4.12.27, cx() in hono/css composes class names from plain strings but marks the result as already escaped without HTML-escaping the input, allowing untrusted className values used in a JSX class attribute during server-side rendering to break out of the attribute and inject arbitrary markup. This issue is fixed in version 4.12.27.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00327 25th percentileScored 2026-11-07

Fix Partial hono (honojs): 4.12.27hono (npm): 4.12.27Red Hat: 4 without a fix

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	4.0.0 to before 4.12.27	4.12.27	Patch available	CNA
—	hono (npm)	4.0.0 to before 4.12.27	4.12.27	Patch available	GHSA-w62v-xxxg-mg59

hono Vendorhonojs Affected 4.0.0 to before 4.12.27 Fixed in 4.12.27 Patch available CNA
hono (npm) Vendor— Affected 4.0.0 to before 4.12.27 Fixed in 4.12.27 Patch available GHSA-w62v-xxxg-mg59

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:hono:hono::::::node.js::*	4.0.0 to before 4.12.27	Vulnerable	honojs

cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:* Versions 4.0.0 to before 4.12.27 Vulnerable ·honojs

Remediation

Fix · CNA hono (honojs) Fixed in 4.12.27
Fix · GHSA-w62v-xxxg-mg59 hono (npm) Fixed in 4.12.27 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Migration Toolkit for Applications 8	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat Developer Hub 1	Affected	No fix yet: Fix deferred
Red Hat OpenShift Dev Spaces	Affected	No fix yet: Fix deferred

Not affected: 1 product

Red Hat Hardened Images

Timeline

2026-10-02 Threatist record created from CVE-2026-59895
2026-10-03 Alias added: GHSA-w62v-xxxg-mg59
2026-10-27 Affected versions changed · Red Hat

References

Patch 1

https://github.com/honojs/hono/commit/cd3f6f7194f0e5c9d4b26ae0cf232018d0f388fc

Advisory 2

Other 2

TI-2024-21741 Hono vulnerable to Restricted Directory Traversal in serveStatic with deno 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-2026-23190 Hono: Arbitrary file access via serveStatic vulnerability CVSS 3.1CRITICAL 9.8
TI-2026-22076 Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo CVSS 3.1HIGH 8.2
TI-2026-18334 JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback) CVSS 3.1HIGH 8.2

See all 33 →

Sources

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