CVE-2026-24473: 
JavaScript vulnerability analysis and mitigation

CVE-2026-24473 is an information disclosure vulnerability in the Serve Static Middleware of the Hono web framework's Cloudflare Workers adapter, allowing unauthenticated attackers to read arbitrary keys from the Workers environment. The flaw affects all Hono versions prior to 4.11.7 (npm package) and was disclosed on January 27, 2026, by maintainer yusukebe via a GitHub Security Advisory. It carries a CVSS v3.1 base score of 5.3 (Medium) and a CVSS v4.0 base score of 6.3 (Medium) (Github Advisory, Hono Security Advisory). IBM watsonx Orchestrate with watsonx Assistant Cartridge is also listed as an affected downstream product (IBM Advisory).

The root cause is improper validation of user-controlled request paths in the getContentFromKVAsset function within src/adapter/cloudflare-workers/utils.ts (CWE-200, CWE-284, CWE-668). In vulnerable versions, the code used ASSET_MANIFEST[path] || path as the KV storage key, meaning that if a path was not found in the asset manifest, the raw user-supplied path was used directly as the KV key — potentially exposing arbitrary keys stored in the Workers environment. The fix (commit cf9a78d) changes this to ASSET_MANIFEST[path] only, so unrecognized paths return null instead of falling back to the raw input (Hono Security Advisory, Patch Commit). Exploitation requires no authentication, no user interaction, and is performed over the network, but is limited to applications running on Cloudflare Workers that use Serve Static Middleware with user-controllable request paths.

Successful exploitation allows an unauthenticated remote attacker to read arbitrary keys from the Cloudflare Workers KV asset storage, potentially exposing sensitive configuration details, internal asset keys, and credentials stored in the Workers environment. The impact is strictly limited to confidentiality — attackers cannot modify stored data, execute arbitrary code, or affect availability. The vulnerability scope is confined to applications using Hono's Serve Static Middleware on the Cloudflare Workers adapter that expose user-controlled paths (Github Advisory).

No public proof-of-concept exploit code is known to exist, and there is no evidence of in-the-wild exploitation at this time (Github Advisory). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.012–0.016% (4th percentile), indicating a low probability of exploitation in the near term. The vulnerability was reported by researchers kilkat and JungJoonWoo (Hono Security Advisory).

1. Reconnaissance: Identify web applications running on Cloudflare Workers that use the Hono framework (npm package hono < 4.11.7) with Serve Static Middleware and user-controllable request paths.
2. Identify target endpoint: Locate the static asset serving endpoint exposed by the Hono application (e.g., a route serving files from Workers KV storage).
3. Craft malicious request: Send an HTTP GET request with a path that does not correspond to any legitimate static asset but matches a known or guessed internal KV key (e.g., GET /internal-config-key or GET /secret-env-value).
4. Exploit fallback behavior: In vulnerable versions, if the path is not found in ASSET_MANIFEST, the raw path is used directly as the KV storage key (ASSET_MANIFEST[path] || path), causing the middleware to fetch and return the content of that arbitrary key.
5. Retrieve sensitive data: The response body contains the value associated with the arbitrary KV key, potentially exposing internal configuration, credentials, or other sensitive data stored in the Workers environment (Hono Security Advisory, Patch Commit).

• Network: Unusual HTTP GET requests to static asset endpoints with paths that do not correspond to known static files or assets (e.g., paths resembling internal configuration keys, environment variable names, or non-standard resource identifiers).
• Logs: Cloudflare Workers request logs showing repeated requests to the static middleware with non-standard or unexpected path values; responses returning content for paths not present in the asset manifest.
• Application Behavior: Unexpected KV storage reads for keys outside the normal static asset namespace, observable via Cloudflare Workers analytics or KV access logs if enabled.

Upgrade the Hono npm package to version 4.11.7 or later, which contains the fix for this vulnerability (Hono Release v4.11.7). The patch is also available via commit cf9a78db4d0a19b117aee399cbe9d3a6d9bfd817 (Patch Commit). As an interim workaround, implement strict server-side validation of request paths before they reach the Serve Static Middleware, ensuring only paths present in the asset manifest are processed. Additionally, audit all keys stored in the Workers KV environment to identify any sensitive data that may have been exposed, and review access logs for anomalous path requests.

The advisory was published by Hono maintainer yusukebe as part of a broader v4.11.7 security release that addressed multiple vulnerabilities including an IP restriction bypass (CVE-2026-24398), a cache middleware issue (CVE-2026-24472), and an XSS in the ErrorBoundary component (Hono Release v4.11.7). IBM subsequently issued advisories noting that its watsonx Orchestrate with watsonx Assistant Cartridge product is affected by this CVE (IBM Advisory). Community reaction on GitHub was modest, with the release receiving a small number of positive reactions, consistent with the moderate severity rating.