Prototype pollution via inherited bracket-key traversal
Published May 29, 2026 · Updated May 29, 2026
Prototype pollution in form-data-objectizer before 1.0.1 allows remote attackers to alter inherited properties via crafted form keys. In index.cjs, treatInitial and treatSecond use prototype-chain-aware membership tests and recursively assign unfiltered proto, constructor, or prototype path segments into Object.prototype. Reachability requires a Node.js application to pass attacker-controlled FormData to toObject(); pollution persists for the worker lifetime and can corrupt subsequent object property reads or crash the worker.
Summary
What happened
Prototype pollution in form-data-objectizer before 1.0.1 allows remote attackers to alter inherited properties via crafted form keys. In index.cjs, treatInitial and treatSecond use prototype-chain-aware membership tests and recursively assign unfiltered proto, constructor, or prototype path segments into Object.prototype. Reachability requires a Node.js application to pass attacker-controlled FormData to toObject(); pollution persists for the worker lifetime and can corrupt subsequent object property reads or crash the worker.
The record
- CVE
- CVE-2026-46510
- Published
- May 29, 2026
- Updated
- May 29, 2026
- Vendor
- Kasper Stöckel
- Product
- form-data-objectizer
- Classifications
- CWE-1321, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 29, 2026CVE publishedPublication date reported by the CVE source.
- May 29, 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=< 1.0.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- GHSA-m2hg-wjq3-28wq proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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