Hono up to 4.12.6 Form Field Parser parseBody field name prototype pollution

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.0$0-$5k1.20+

Summaryinfo

A vulnerability categorized as critical has been discovered in Hono up to 4.12.6. The affected element is the function parseBody of the component Form Field Parser. Executing a manipulation of the argument field name can lead to prototype pollution. This vulnerability is tracked as CVE-2026-56763. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in Hono up to 4.12.6. This vulnerability affects the function parseBody of the component Form Field Parser. The manipulation of the argument field name with an unknown input leads to a prototype pollution vulnerability. The CWE definition for the vulnerability is CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-56763 since 06/22/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.

Upgrading to version 4.12.7 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Prototype pollution
CWE: CWE-1321 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: Hono 4.12.7

Timelineinfo

06/22/2026 CVE reserved
07/11/2026 +19 days Advisory disclosed
07/11/2026 +0 days VulDB entry created
07/11/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-56763 (🔒)
GCVE (CVE): GCVE-0-2026-56763
GCVE (VulDB): GCVE-100-377812

Entryinfo

Created: 07/11/2026 15:49
Changes: 07/11/2026 15:49 (54)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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