CVE-2026-56763 PUBLISHED

Hono - Prototype Pollution via proto Key in parseBody with dot Option

Assigner: VulnCheck
Reserved: 22.06.2026 Published: 11.07.2026 Updated: 11.07.2026

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.

CVSS Vector: 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
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	None
Attack Complexity	High	Integrity	Low	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS Score: 4.8

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	Low
Privileges Required	None	Integrity Impact	Low
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	Hono
Product	Hono
Versions	Default: unaffected affected from 0 to 4.12.7 (excl.) Version 4.12.7 is unaffected

Credits

0xkakash1 reporter

References

Problem Types

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') CWE