Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion (CVE-2026-84364) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-84364

Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion

Answer in brief

CVE-2026-84364 records a Unknown severity vulnerability in Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion. The current sources do not mark it as known exploited. The current feed maps honojs/hono (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 1, 2026Updated Sep 1, 2026Source checked Sep 1, 2026First seen by HOL Sep 1, 2026Material review Sep 1, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps honojs/hono (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
honojs/honogeneric	< 4.13.5	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for honojs/hono.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Sep 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 1, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.