Hono vulnerable to XSS through ErrorBoundary component
Summary
A Cross-Site Scripting (XSS) vulnerability exists in the ErrorBoundary component of the hono/jsx library. Under certain usage patterns, untrusted user-controlled strings may be rendered as raw HTML, allowing arbitrary script execution in the victim's browser.
Details
The issue is in the ErrorBoundary component (src/jsx/components.ts). ErrorBoundary previously forced certain rendered output paths to be treated as raw HTML, bypassing the library's default escaping behavior. This could result in unescaped rendering when developers pass user-controlled strings directly as children, or when fallbackRender returns user-controlled strings (for example, reflecting error messages that contain attacker input).
This vulnerability is only exploitable when an application renders untrusted user input within ErrorBoundary without appropriate escaping or sanitization.
Impact
Successful exploitation may allow attackers to execute arbitrary JavaScript in the victim’s browser (reflected XSS). Depending on the application context, this can lead to actions such as session compromise, data exfiltration, or performing unauthorized actions as the victim.
Affected Components
- hono/jsx:
ErrorBoundarycomponent
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | hono | < 4.11.7 | 4.11.7 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
hono- Disclosed
- 28.01.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-9r54-q6cx-xmh5 - CC BY 4.0
Vulnerability history: hono
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 52
- First → latest
- 12.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 7
- Medium 41
- Low 4
Disclosures per year
- 2023: 1
- 2024: 3
- 2025: 4
- 2026: 44
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