CVE-2026-44456 — hono
MEDIUMCVE-2026-44456 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in hono. A fix is available for hono — see the affected versions and patch details below.
Hono: bodyLimit() can be bypassed for chunked / unknown-length requests
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44456.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-44456 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
hononpmDescription
Summary
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.
Impact
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.
Credits
- @lalalala5678 (slow chunked / early return variants)
- @Jvr2022 (error handling bypass)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.12.16npm install hono@4.12.16 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update hono to 4.12.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44456 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-44456 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-44456. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-44456 in your dependencies?
O3 Security finds CVE-2026-44456 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.