hono/jsx renders plain strings unescaped in boundary components, leading to XSSGHSA-hxh3-vqpv-xpqv
MEDIUMFix: honojs/hono@2b8ed40GHSA-hxh3-vqpv-xpqv is a medium-severity (CVSS 4.7) Cross-site Scripting (XSS) vulnerability in hono. A fix is available for hono — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hxh3-vqpv-xpqv.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-hxh3-vqpv-xpqv by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
hononpmDescription
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 stringfallbackwhile 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.13.7npm install hono@4.13.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hono to 4.13.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hxh3-vqpv-xpqv is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is evaluated as having Moderate severity because successful exploitation requires specific application rendering contexts where unescaped user input is directly evaluated by server-side template boundaries. Within Red Hat supported products, the affected package is included as an embedded dependency…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for GHSA-hxh3-vqpv-xpqv (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Hardened Images | grafana13-2-main-13.2.1-0.7.hum1 | RHSA-2026:71906 |
| Red Hat Hardened Images | grafana12-4-main-12.4.10-0.10.hum1 | RHSA-2026:73654 |
| Red Hat Hardened Images | grafana13-1-main-13.1.6-0.5.hum1 | RHSA-2026:73655 |
| Red Hat Hardened Images | grafana13-1-main-13.1.6-0.6.hum1 | RHSA-2026:74869 |
Frequently Asked Questions
Is GHSA-hxh3-vqpv-xpqv in your dependencies?
Find it across npm, including transitive dependencies.