SEPTEMBER 17, 2026
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Case File

CVE-2026-84363

MEDIUM · CVSS 5.9 EPSS 0.34% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-01 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

The Hono web application framework prior to version 4.13.5 is vulnerable due to improper handling of hash fragments in query parameters, which can lead to unauthorized access to request parameters and potentially allow stored cross-site scripting (XSS) attacks. This vulnerability can result in poisoned cached responses, affecting users who receive these responses without proper filtering. Organizations using affected versions of Hono should prioritize upgrading to version 4.13.5 to mitigate these risks, especially those relying on caching mechanisms and handling user-generated content.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-84363
Severity
MEDIUM
CVSS
5.9
EPSS
0.34%
Java

Original NVD Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.5, Hono's query helpers treat a question mark after a literal hash fragment as the start of a query string, so the application can read request parameters that browsers, new URL(), reverse proxies, filtering rules, parameter allow and deny lists, access logging, request validation, and other middleware do not observe. The Cache Middleware removes the fragment when building its cache key, allowing a response influenced by parameters inside the fragment to be stored under a key that omits those parameters and later served to other users. This can bypass filtering and auditing, poison cached responses, and enable stored cross-site scripting when an affected parameter is reflected into cached HTML without escaping. Exploitation requires a runtime and intermediary path that passes a literal hash character through to the request URL; Cloudflare Workers and intermediaries that strip fragments are not affected. This issue is fixed in version 4.13.5.