CVE-2026-49250 Conform: parseSubmission vulnerable to CPU exhaustion when parsing many unique form fields
An unauthenticated attacker can cause CPU exhaustion and denial of service by submitting a form with many unique field names to applications using the Conform library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49250?
CVE-2026-49250 is a high-severity denial of service vulnerability in edmundhung conform, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-407
Which versions are affected by CVE-2026-49250?
2 open source packages ship an affected version, including @conform-to/dom.
| Package | Affected | Fixed in |
|---|---|---|
@conform-to/dom npm | From 1.8.0 | 1.19.4 |
@conform-to/dom npm | From 1.8.0 | 1.19.4 |
How do I fix CVE-2026-49250?
Upgrade @conform-to/dom to 1.19.4 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-49250 being exploited?
There is no known exploitation of CVE-2026-49250 in the wild and no public exploit code.
Sources
Also known as GHSA-525m-7f82-2mf7.