What’s Vulnerable › Vulnerabilities

CVE-2026-49250: Conform: parseSubmission vulnerable to CPU exhaustion when parsing many unique form fields

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-14 · updated 2026-09-30
• Weakness: CWE-407

Description

Conform, a type-safe form validation library, allows the parsing of nested objects in the form of object.property. From 1.8.0 until 1.19.4, the parseSubmission future API in packages/conform-dom/formdata.ts repeatedly scans FormData or URLSearchParams entries by each unique field name. An unauthenticated attacker can submit a crafted form containing many unique names, causing excessive synchronous CPU work and denial of service in an application that passes the submission to parseSubmission. Applications should continue to enforce request parsing limits before invoking Conform. This issue is fixed in version 1.19.4.

Affected products

• edmundhung conform: from 1.8.0, < 1.19.4

References

• https://github.com/edmundhung/conform/commit/f9a1e696ef950efcada5f06ea2b202da505bf9b0
• https://github.com/edmundhung/conform/releases/tag/v1.19.4
• https://github.com/edmundhung/conform/security/advisories/GHSA-525m-7f82-2mf7

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