CVE-2026-44456

bodyLimit() does not reliably enforce maxSize for requests without a usable Content-Length (e.g. Transfer-Encoding: chunked). Oversized requests can reach handlers and return 200 instead of 413.

Details

For chunked / unknown-length requests, bodyLimit() wraps the body in a stream that counts bytes asynchronously, then runs the handler before the size decision is final. The 413 is only applied afterwards by checking c.error.

This lets the limit be bypassed when:

• the handler does not read the body,
• the handler reads only the first chunk(s) and returns, or
• the handler reads the body but swallows the read error in try/catch.

In all three cases the handler returns 200 before the limit check completes (or its result is observed).

The fix is to enforce the size decision before next() runs, instead of retrofitting the response via c.error afterwards.

Credits

• @lalalala5678 (slow chunked / early return variants)
• @Jvr2022 (error handling bypass)

Applications relying on bodyLimit() as a hard boundary can be bypassed: oversized chunked requests can reach handler logic and return successful responses. Per-request data exposure is bounded by maxSize, but the documented guarantee, "oversized requests are rejected before business logic runs", does not hold.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2026-44456 has a CVSS score of 6.5 (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 (4.12.16); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44456? CVE-2026-44456 is a medium-severity uncontrolled resource consumption vulnerability in hono (npm), affecting versions < 4.12.16. It is fixed in 4.12.16. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
2. How severe is CVE-2026-44456? CVE-2026-44456 has a CVSS score of 6.5 (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-2026-44456? hono (npm) versions < 4.12.16 is affected.
4. Is there a fix for CVE-2026-44456? Yes. CVE-2026-44456 is fixed in 4.12.16. Upgrade to this version or later.
5. Is CVE-2026-44456 exploitable, and should I be worried? Whether CVE-2026-44456 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-2026-44456 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-2026-44456? Upgrade hono to 4.12.16 or later.