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CVE-2026-93981 medium CVSS 4.7

Cross-Site Scripting (XSS) in hono (CVE-2026-93981)

Summary

Cross-site scripting in hono (CVE-2026-93981). Risk of unauthorized operations or information disclosure. Exploitable via fallback. Mitigation: upgrade to 4.11.7 or later.

Original description

The description as published by the source.

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.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-93981 has been found in hono.
Attackers can target a specific entry point like fallback over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.7/10.
What to do: upgrade hono to 4.11.7 or later.
If unsure, ask your IT team or search "hono CVE-2026-93981" on the vendor's site.

CVE-2026-93981 (hono) — CWE-79 / CVSS v3 4.7
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: fallback / Suspense / ErrorBoundary / Context.Provider
Patched: 4.11.7 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Cross-site scripting (XSS) (CWE-79) exists in hono. Attackers reach the vulnerable code path via fallback without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of hono. Attack surface: fallback / Suspense / ErrorBoundary / Context.Provider.

🔥 Severity

Severity: Medium (CVSS 4.7/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 4.11.7.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'hono' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'hono' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で hono を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade hono to 4.11.7

    ステージング環境で 4.11.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm hono
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.13.7"}]}]

References

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