🛡️ CVE-2026-44458 — hono

🟡 CVSS 4.3 — Medium ✅ No Known Exploit CWE-116 OSV
4.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Hono has CSS Declaration Injection via Style Object Values in JSX SSR

Summary

The JSX renderer escapes style attribute object values for HTML but not for CSS. Untrusted input in a style object value or property name can therefore inject additional CSS declarations into the rendered style attribute. The impact is limited to CSS and does not allow JavaScript execution or HTML attribute breakout.

Details

style object values are serialized into a CSS declaration list and escaped for HTML attribute context only. Characters that act as CSS declaration boundaries — such as ;, comment markers, quoted strings, and block delimiters — are valid in HTML attribute content and can extend a value beyond its assigned property.

This issue arises when untrusted input is interpolated into a JSX style object and rendered server-side.

Impact

An attacker who can control the value or property name of a style object may inject arbitrary CSS declarations. This may lead to:

  • Visual manipulation of the page, including full-viewport overlays usable for phishing
  • Outbound requests to attacker-controlled hosts via CSS resource references such as url(...)
  • Hijacking of UI affordances through layout, positioning, or visibility changes

This issue affects applications that render JSX on the server with style object values or property names derived from untrusted input.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability none.

Weakness class

CVE-2026-44458 is classified as CWE-116: Improper Encoding or Escaping of Output. Output is emitted without encoding it for the context it lands in, so data is interpreted as markup or code.

Affected software

CVE-2026-44458 is recorded against 1 package.

  • hono

Timeline and source

Published on 9 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Package)

CVE-2026-44458 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 4.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CWE CWE-116
Public Exploit ✅ No
Source OSV
Published 2026-05-09
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
hono — —

Similar Threats

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