Medium
Hono - Prototype Pollution via __proto__ Key in parseBody with dot Option
Type: advisorySources: OSV
Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled, permitting specially crafted form field names to create objects with __proto__ properties. When parsed results are merged into regular JavaScript objects using unsafe merge patterns, attackers can exploit this to achieve prototype pollution and modify object behavior.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-56763
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 15:18 UTC · Revision 1
Source evidence
Hono - Prototype Pollution via __proto__ Key in parseBody with dot Option
core-osv · Original sourcePublished 11 Jul 2026, 13:00 UTC
Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled, permitting specially crafted form field names to create objects with __proto__ properties. When parsed results are merged into regular JavaScript objects using unsafe merge patterns, attackers can exploit this to achieve prototype pollution and modify object behavior.
osv:CVE-2026-56763
Complete source record
{
"id": "815ccd0896682d28f55be79bb34fe07f61f8afa7cd29a63f26aa7c5272701319",
"url": "https://osv.dev/vulnerability/CVE-2026-56763",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Hono - Prototype Pollution via __proto__ Key in parseBody with dot Option",
"summary": "Hono before 4.12.7 allows __proto__ key in parseBody with dot option enabled, permitting specially crafted form field names to create objects with __proto__ properties. When parsed results are merged into regular JavaScript objects using unsafe merge patterns, attackers can exploit this to achieve prototype pollution and modify object behavior.",
"evidence": "osv:CVE-2026-56763",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-56763",
"aliases": [
"CVE-2026-56763",
"GHSA-v8w9-8mx6-g223"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/honojs/hono",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "b0aba5bd76f11a9f0fef1210a705523fa30172ab"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "4.12.7"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
},
{
"range": [
{
"introduced": "0"
},
{
"fixed": "4.12.7"
}
],
"source": "DESCRIPTION"
}
]
}
}
],
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"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56763.json"
}
}
],
"modified": "2026-10-28T02:30:29.679468508Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56763.json",
"https://github.com/honojs/hono/security/advisories/GHSA-v8w9-8mx6-g223",
"https://nvd.nist.gov/vuln/detail/CVE-2026-56763",
"https://www.vulncheck.com/advisories/hono-prototype-pollution-via-proto-key-in-parsebody-with-dot-option"
],
"provider_metadata": {
"cwe_ids": [
"CWE-1321"
],
"cna_assigner": "VulnCheck",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56763.json"
}
},
"related_cves": [
{
"value": "CVE-2026-56763",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 496750,
"published_at": "2026-07-11T13:00:59.084+00:00"
}