CVE-2026-84364 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in hono. O3 Security confirms whether CVE-2026-84364 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion
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-2026-84364.
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
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.5, when parseBody() expands dot-separated form field names into nested objects with dot-notation parsing enabled, it does not limit the nesting depth or the total number of intermediate objects created. Empty segments are preserved, so one deeply dotted field name can encode one nesting level per byte, while a large number of shallowly dotted fields can create the same amplification across a request. A request body within a normal size limit can therefore allocate an object graph far larger than the request after the body has already been accepted. An unauthenticated attacker who can reach an affected endpoint can send concurrent requests that exhaust the JavaScript heap, terminate the server process, and leave the service unavailable until restart. Dot-notation parsing is not enabled by default, and applications using the default behavior are not affected. This issue is fixed in version 4.13.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.13.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hono to 4.13.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-84364 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 pinpoints whether CVE-2026-84364 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-84364. 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-2026-84364 in your dependencies?
O3 detects CVE-2026-84364 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.