GHSA-G6GW-C38X-MQFC
Vulnerability from github – Published: 2026-09-08 21:23 – Updated: 2026-09-08 21:23Summary
When parseBody() expands dot-separated form field names into nested objects, it does not limit the nesting depth or the total number of objects created. A request body well within a normal size limit can therefore allocate an object graph far larger than the request itself, and concurrent requests can exhaust the heap and terminate the process.
Details
Each dot-separated segment of a field name creates an intermediate object. Neither the segments within a single field name nor the total across a request was bounded, and empty segments were preserved, so a field name could encode one nesting level per byte.
Both shapes produce the effect: a single deeply dotted field name, and a large number of shallowly dotted ones within one body. A request body size limit does not prevent it, because the amplification happens after the body has been accepted.
Dot-notation parsing is not enabled by default.
Impact
An attacker who can reach an endpoint that parses request bodies with dot-notation enabled can send concurrent requests whose memory cost is disproportionate to their size.
This may lead to:
- exhaustion of the JavaScript heap and termination of the server process
- the service remaining unavailable until it is restarted
This issue affects applications that explicitly enable dot-notation parsing. Applications using the default behaviour are not affected.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "hono"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.13.5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-84364"
],
"database_specific": {
"cwe_ids": [
"CWE-400"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-08T21:23:02Z",
"nvd_published_at": "2026-09-01T21:18:47Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nWhen `parseBody()` expands dot-separated form field names into nested objects, it does not limit the nesting depth or the total number of objects created. A request body well within a normal size limit can therefore allocate an object graph far larger than the request itself, and concurrent requests can exhaust the heap and terminate the process.\n\n### Details\n\nEach dot-separated segment of a field name creates an intermediate object. Neither the segments within a single field name nor the total across a request was bounded, and empty segments were preserved, so a field name could encode one nesting level per byte.\n\nBoth shapes produce the effect: a single deeply dotted field name, and a large number of shallowly dotted ones within one body. A request body size limit does not prevent it, because the amplification happens after the body has been accepted.\n\nDot-notation parsing is not enabled by default.\n\n### Impact\n\nAn attacker who can reach an endpoint that parses request bodies with dot-notation enabled can send concurrent requests whose memory cost is disproportionate to their size.\n\nThis may lead to:\n\n- exhaustion of the JavaScript heap and termination of the server process\n- the service remaining unavailable until it is restarted\n\nThis issue affects applications that explicitly enable dot-notation parsing. Applications using the default behaviour are not affected.",
"id": "GHSA-g6gw-c38x-mqfc",
"modified": "2026-09-08T21:23:02Z",
"published": "2026-09-08T21:23:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/honojs/hono/security/advisories/GHSA-g6gw-c38x-mqfc"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84364"
},
{
"type": "WEB",
"url": "https://github.com/honojs/hono/commit/531e9c5a3ae058d10de33f643055bd4009a87178"
},
{
"type": "PACKAGE",
"url": "https://github.com/honojs/hono"
},
{
"type": "WEB",
"url": "https://github.com/honojs/hono/releases/tag/v4.13.5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
"type": "CVSS_V3"
}
],
"summary": "Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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