Prototype pollution via unfiltered __proto__ path segment
Published Jul 11, 2026 · Updated Jul 11, 2026
Prototype pollution in Hono before 4.12.7 allows remote attackers to alter object behavior through crafted form field names. The HonoRequest parseBody({ dot: true }) path builder accepts an unfiltered proto segment and constructs an object containing that property. Exploitation requires an application to enable dot parsing and merge the parsed form data into a regular object with an unsafe pattern, allowing attacker-controlled prototype attributes to affect later application logic.
Summary
What happened
Prototype pollution in Hono before 4.12.7 allows remote attackers to alter object behavior through crafted form field names. The HonoRequest parseBody({ dot: true }) path builder accepts an unfiltered proto segment and constructs an object containing that property. Exploitation requires an application to enable dot parsing and merge the parsed form data into a regular object with an unsafe pattern, allowing attacker-controlled prototype attributes to affect later application logic.
The record
- CVE
- CVE-2026-56763
- Published
- Jul 11, 2026
- Updated
- Jul 11, 2026
- Vendor
- Hono
- Product
- Hono
- Classifications
- CWE-1321, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 11, 2026CVE publishedPublication date reported by the CVE source.
- Jul 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <4.12.7
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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