CVE-2026-24472: 
JavaScript vulnerability analysis and mitigation

CVE-2026-24472 is a Web Cache Deception vulnerability in the Hono web application framework's Cache Middleware that causes information disclosure by improperly handling HTTP cache control directives. The middleware fails to respect Cache-Control: private and Cache-Control: no-store headers, potentially exposing private or authenticated responses to unauthorized users. It affects all Hono versions prior to 4.11.7 (npm package) and was disclosed on January 27, 2026, by researcher simonkoeck. It carries a CVSS v3.1 base score of 5.3 (Medium) (Github Advisory, Hono Security Advisory).

The root cause lies in the shouldSkipCache function within Hono's Cache Middleware (src/middleware/cache/index.ts), classified as CWE-524 (Use of Cache Containing Sensitive Information) and CWE-613 (Insufficient Session Expiration). Prior to the fix, the function only checked for Vary: * headers when deciding whether to skip caching, completely ignoring Cache-Control: private, Cache-Control: no-store, and Set-Cookie headers. The vulnerability specifically affects applications running on Deno, Bun, and Node.js runtimes, as Cloudflare Workers enforces cache control restrictions at the platform level independently. An attacker can exploit this by making an unauthenticated request to a URL previously accessed by an authenticated user, receiving the cached sensitive response (Hono Security Advisory, Patch Commit).

Successful exploitation allows unauthenticated attackers to retrieve cached responses intended only for authenticated users, potentially exposing personally identifiable information (PII) and session-related data. There is no integrity or availability impact; the vulnerability is limited to confidentiality. The attack scope is restricted to applications that use the hono/cache middleware on Deno, Bun, or Node.js runtimes and rely on the middleware to honor HTTP cache control directives (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. The vulnerability requires no authentication, no user interaction, and is exploitable over the network with low attack complexity, making it straightforward to attempt once an attacker identifies a vulnerable deployment. The EPSS score is approximately 0.016% (4th percentile), indicating a low near-term exploitation probability. It is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (Github Advisory).

1. Reconnaissance: Identify web applications built with the Hono framework (npm package hono < 4.11.7) running on Deno, Bun, or Node.js runtimes that use the Cache Middleware.
2. Identify target endpoints: Locate authenticated endpoints that return user-specific or sensitive data (e.g., profile pages, account details) and that set Cache-Control: private or Cache-Control: no-store response headers.
3. Trigger caching: Wait for or induce an authenticated user to access the target endpoint, causing the vulnerable middleware to cache the private response despite the cache control directives.
4. Access cached response: Send an unauthenticated HTTP GET request to the same URL. Because the middleware incorrectly cached the authenticated response, the server returns the cached sensitive data to the unauthenticated requester.
5. Extract sensitive data: Parse the response for PII, session tokens, or other sensitive information that was intended only for the authenticated user (Hono Security Advisory, Patch Commit).

• Network: Repeated unauthenticated HTTP GET requests to endpoints that normally require authentication, particularly if those requests return HTTP 200 with user-specific content; unusual access patterns where the same URL is accessed by both authenticated and unauthenticated clients in quick succession.
• Logs: Application or access logs showing unauthenticated requests receiving 200 OK responses with content-type and body consistent with authenticated user data; absence of Authorization or session cookie headers in requests that return sensitive data.
• Application Behavior: Responses containing Cache-Control: private or Cache-Control: no-store headers being served from cache (e.g., presence of cache hit indicators in response headers) on affected runtimes (Deno, Bun, Node.js).

The primary remediation is to upgrade the Hono npm package to version 4.11.7 or later, which patches the shouldSkipCache function to correctly skip caching for responses with Cache-Control: private, Cache-Control: no-store, no-cache="Set-Cookie", or a Set-Cookie header (Hono Release v4.11.7, Patch Commit). As a temporary workaround for applications unable to upgrade immediately, implement cache control enforcement at the infrastructure level (e.g., reverse proxy or CDN rules) and audit sensitive endpoints to ensure they are not inadvertently cached. IBM has also released patches for affected IBM watsonx Orchestrate with watsonx Assistant Cartridge products (IBM Advisory 1, IBM Advisory 2).

The vulnerability was reported by security researcher simonkoeck and published by Hono maintainer yusukebe as part of a broader security release (v4.11.7) that addressed multiple vulnerabilities simultaneously, including an IP restriction bypass and an XSS issue (Hono Release v4.11.7). The release received positive community engagement on GitHub with reactions from multiple contributors. No significant broader media coverage or notable social media commentary beyond standard CVE tracking feeds has been identified.