GHSA-HXH3-VQPV-XPQV

Vulnerability from github – Published: 2026-09-30 23:46 – Updated: 2026-09-30 23:46
VLAI
Summary
hono/jsx renders plain strings unescaped in boundary components, leading to XSS
Details

Summary

hono/jsx does not HTML-escape a plain string placed directly as a child or fallback of Suspense or ErrorBoundary, as the only child of a Context.Provider, or as the root value of renderToString() / renderToReadableStream() from hono/jsx/dom/server. Such a string is emitted as markup instead of text.

Details

These paths stringify their input and treat the result as already-escaped HTML, so a plain string passes through unchanged. Notable cases:

  • Suspense: a string child, or a string fallback while a child suspends. With streaming, the fallback reaches the browser in the initial chunk.
  • ErrorBoundary: a string child alongside an asynchronous sibling. The all-synchronous case was fixed in 4.11.7 (GHSA-9r54-q6cx-xmh5).
  • Context.Provider: a single string child. Multiple children are escaped.
  • hono/jsx/dom/server: a string, or an array containing strings, passed as the root.

A lone {children} forwarded by a wrapper component is enough to reach these paths. Strings wrapped in an element, values from raw() or the html helper, and client-side rendering with hono/jsx/dom are not affected.

Impact

An attacker who controls a string rendered in an affected position can inject arbitrary HTML into the server-rendered page, leading to cross-site scripting under the application's origin.

This issue affects applications that render untrusted strings directly in one of the positions above during server-side rendering.

Severity
4.7 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "hono"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.13.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-93981"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-30T23:46:16Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`hono/jsx` does not HTML-escape a plain string placed directly as a child or `fallback` of `Suspense` or `ErrorBoundary`, as the only child of a `Context.Provider`, or as the root value of `renderToString()` / `renderToReadableStream()` from `hono/jsx/dom/server`. Such a string is emitted as markup instead of text.\n\n### Details\n\nThese paths stringify their input and treat the result as already-escaped HTML, so a plain string passes through unchanged. Notable cases:\n\n- `Suspense`: a string child, or a string `fallback` while a child suspends. With streaming, the fallback reaches the browser in the initial chunk.\n- `ErrorBoundary`: a string child alongside an asynchronous sibling. The all-synchronous case was fixed in 4.11.7 (GHSA-9r54-q6cx-xmh5).\n- `Context.Provider`: a single string child. Multiple children are escaped.\n- `hono/jsx/dom/server`: a string, or an array containing strings, passed as the root.\n\nA lone `{children}` forwarded by a wrapper component is enough to reach these paths. Strings wrapped in an element, values from `raw()` or the `html` helper, and client-side rendering with `hono/jsx/dom` are not affected.\n\n### Impact\n\nAn attacker who controls a string rendered in an affected position can inject arbitrary HTML into the server-rendered page, leading to cross-site scripting under the application\u0027s origin.\n\nThis issue affects applications that render untrusted strings directly in one of the positions above during server-side rendering.",
  "id": "GHSA-hxh3-vqpv-xpqv",
  "modified": "2026-09-30T23:46:16Z",
  "published": "2026-09-30T23:46:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/security/advisories/GHSA-hxh3-vqpv-xpqv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93981"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/commit/2b8ed402cdab6dfc5e829b480806dcd8db94161e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/honojs/hono"
    },
    {
      "type": "WEB",
      "url": "https://github.com/honojs/hono/releases/tag/v4.13.7"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/hono-jsx-before-4.13.7-cross-site-scripting-via-unescaped-strings"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "hono/jsx renders plain strings unescaped in boundary components, leading to XSS"
}



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