CVE-2026-56761: Hono Hono Improperly Handles JSX Attribute Vulnerability

MODERATE
Advisory Identifier: GHSA-458j-xx4x-4375
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CVSS 4.3
CWE-79
Published
Advisory Summary

CVE-2026-56761 is a MODERATE (CVSS 4.3) hono improperly handles jsx attribute vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Hono libraries in the npm ecosystem. The issue involves hono improperly handles jsx attribute names allows html injection in hono/jsx ssr. Remediation is available by upgrading affected packages to version 4.12.14.

CVE-2026-56761 at a Glance

CVE Identifier CVE-2026-56761
GHSA Identifier GHSA-458j-xx4x-4375
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Hono
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 4.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-56761

To remediate this vulnerability, upgrade all affected Hono dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

hono fixed: 4.12.14 
npm install hono@4.12.14
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls hono

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-56761, inspect your project dependencies using npm:

npm ls hono

Analyze the terminal output to locate any version of Hono in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.12.14), your application is affected.

Note: The npm ls hono command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Hono, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Summary Improper handling of JSX attribute names in hono/jsx allows malformed attribute keys to corrupt the generated HTML output. When untrusted input is used as attribute keys during server-side rendering, specially crafted keys can break out of attribute or tag boundaries and inject unintended HTML. ## Details When rendering JSX elements to HTML strings, attribute values are escaped, but attribute names (keys) were previously inserted into the output without validation. If an attribute name contains characters such as `"`, `>`, or whitespace, it can alter the structure of the generated HTML. For example, malformed attribute names can: * Break out of the current attribute and introduce unintended additional attributes * Break out of the current HTML tag and inject new elements into the output This issue arises when untrusted input (such as query parameters or form data) is used as JSX attribute keys during server-side rendering. ## Impact An attacker who can control attribute keys used in JSX rendering may inject unintended attributes or HTML elements into the generated output. This may lead to: * Injection of unexpected HTML attributes * Corruption of the HTML structure * Potential cross-site scripting (XSS) if combined with unsafe usage patterns This issue affects applications that pass untrusted input as JSX attribute keys during server-side rendering.

CVE-2026-56761 Affected Hono Versions

1 component(s)
Fixed Versions:
4.12.14
Product / Package Ecosystem Affected Versions Fixed Version
hono
npm/hono
npm
< 4.12.14
4.12.14

References

GitHub Advisory / Wiki ADVISORY
https://github.com/honojs/hono/security/advisories/GHSA-458j-xx4x-4375
Hono Source Repository REPOSITORY
https://github.com/honojs/hono

Frequently Asked Questions

What is CVE-2026-56761?
CVE-2026-56761 is a security vulnerability in Hono involving hono Improperly Handles JSX Attribute Names Allows HTML Injection in hono/jsx SSR under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Hono versions are affected?
Affected versions include releases prior to 4.12.14 across affected packages: hono.
What version fixes CVE-2026-56761?
Upgrading to 4.12.14 (or the latest patched release for your respective branch) resolves the vulnerability.
Is hono affected?
Yes, hono is affected in releases prior to 4.12.14. Upgrade your dependency to 4.12.14 or later.
What is the CVSS score of CVE-2026-56761?
CVE-2026-56761 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-56761?
CVE-2026-56761 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-56761?
Run the dependency tree command: 'npm ls hono'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-458j-xx4x-4375",
  "modified" : "2026-06-24T13:10:57Z",
  "published" : "2026-04-16T01:02:24Z",
  "aliases" : [ "CVE-2026-56761" ],
  "summary" : "hono Improperly Handles JSX Attribute Names Allows HTML Injection in hono/jsx SSR",
  "details" : "## Summary\n\nImproper handling of JSX attribute names in hono/jsx allows malformed attribute keys to corrupt the generated HTML output.\n\nWhen untrusted input is used as attribute keys during server-side rendering, specially crafted keys can break out of attribute or tag boundaries and inject unintended HTML.\n\n## Details\n\nWhen rendering JSX elements to HTML strings, attribute values are escaped, but attribute names (keys) were previously inserted into the output without validation.\n\nIf an attribute name contains characters such as `\"`, `>`, or whitespace, it can alter the structure of the generated HTML.\n\nFor example, malformed attribute names can:\n\n* Break out of the current attribute and introduce unintended additional attributes\n* Break out of the current HTML tag and inject new elements into the output\n\nThis issue arises when untrusted input (such as query parameters or form data) is used as JSX attribute keys during server-side rendering.\n\n## Impact\n\nAn attacker who can control attribute keys used in JSX rendering may inject unintended attributes or HTML elements into the generated output.\n\nThis may lead to:\n\n* Injection of unexpected HTML attributes\n* Corruption of the HTML structure\n* Potential cross-site scripting (XSS) if combined with unsafe usage patterns\n\nThis issue affects applications that pass untrusted input as JSX attribute keys during server-side rendering.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hono"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.12.14"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/honojs/hono/security/advisories/GHSA-458j-xx4x-4375"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/honojs/hono"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-16T01:02:24Z",
    "nvd_published_at" : null
  }
}