CVE-2026-44457

Cache Middleware does not skip caching for responses that declare per-user variance via Vary: Authorization or Vary: Cookie. As a result, a response cached for one authenticated user may be served to subsequent requests from different users.

Details

The Cache Middleware skips caching when a response carries Vary: *, certain Cache-Control directives (private, no-store, no-cache), or Set-Cookie. However, Vary: Authorization and Vary: Cookie, the standard signals defined in RFC 9110 / RFC 9111 to indicate per-user responses, are not treated as cache-skip reasons.

This issue arises when applications use the Cache Middleware on endpoints that return user-specific data and rely on Vary: Authorization or Vary: Cookie to scope the response per user, without also setting Cache-Control: private.

A user may receive a cached response that was originally generated for a different authenticated user. This may lead to:

• Disclosure of personally identifiable information or other user-specific data present in the response body
• Inconsistent or incorrect behavior in user-specific endpoints

This issue affects applications that use the Cache Middleware on endpoints whose responses vary by Authorization or Cookie and that do not also set Cache-Control: private.

CVE-2026-44457 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.12.18); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44457? CVE-2026-44457 is a medium-severity security vulnerability in hono (npm), affecting versions < 4.12.18. It is fixed in 4.12.18.
2. How severe is CVE-2026-44457? CVE-2026-44457 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of hono are affected by CVE-2026-44457? hono (npm) versions < 4.12.18 is affected.
4. Is there a fix for CVE-2026-44457? Yes. CVE-2026-44457 is fixed in 4.12.18. Upgrade to this version or later.
5. Is CVE-2026-44457 exploitable, and should I be worried? Whether CVE-2026-44457 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-44457 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-44457? Upgrade hono to 4.12.18 or later.