CVE-2026-45302 json
Prototype Pollution in parse-nested-form-data via `__proto__` in FormData field names
published 2026-05-18 5 mo ago modified 2026-07-22 3 mo ago also GHSA-xp7r-j8r6-j9h3 , EUVD-2026-33723
- cvss
- 8.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 24%
- public exploits
- 0
- none known
Summary
parse-nested-form-data is a tiny node module for parsing FormData by name into objects and arrays. Prior to version 1.0.1, parseFormData() walks bracket and dot-notation FormData field names into nested objects without filtering reserved property keys. A single FormData field whose name begins with __proto__, or contains .__proto__. mid-path, causes the parser to traverse onto Object.prototype and assign properties there, polluting the prototype chain of every plain object in the running process. This issue has been patched in version 1.0.1.
Patch / fix
- npm parse-nested-form-data 1.0.1
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 5 mo ago
Exploit prediction
0.32% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/milamer/parse-nested-form-data/security/advisories/GHSA-xp7r-j8r6-j9h3 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L |
| GitHub | 3.1 | 8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | parse-nested-form-data | <1.0.1 |
1.0.1 |
Affected products
- milamer parse-nested-form-data
Classification
- Weakness
-
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
References
-
github.com
/milamer/parse-nested-form-data/commit/527ad58eb486e32438f7198fb88315c20449d792
web
-
github.com
/milamer/parse-nested-form-data/security/advisories/GHSA-xp7r-j8r6-j9h3
exploit, web
-
github.com
/milamer/parse-nested-form-data/releases/tag/v1.0.1
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-45302
advisory
-
github.com
/milamer/parse-nested-form-data
package
Sources
- CVE List CVE-2026-45302
- GitHub Advisory GHSA-xp7r-j8r6-j9h3
- NVD CVE-2026-45302
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