CVE-2026-49250 — @conform-to/dom
Fix: edmundhung/conform@f9a1e69CVE-2026-49250 is a CWE-407 vulnerability in @conform-to/dom. A fix is available for @conform-to/dom — see the affected versions and patch details below.
Conform: parseSubmission vulnerable to CPU exhaustion when parsing many unique form fields
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49250.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@conform-to/domnpmDescription
A CPU exhaustion vulnerability exists in Conform's parseSubmission future API when parsing FormData or URLSearchParams submissions with many unique field names. The parser previously looked up values by field name, which could require repeated scans of the submitted entries and cause excessive synchronous CPU work if an attacker supplies a crafted submission.
[!NOTE] The patched version fixes this by iterating submitted entries directly instead of repeatedly looking up values by field name. Applications that accept untrusted form submissions should still enforce request parsing limits before passing data to Conform. For multipart requests, @remix-run/form-data-parser provides
maxParts,maxTotalSize,maxFileSize,maxFiles, andmaxHeaderSizeoptions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @conform-to/dom | ≥ 1.8.0&&< 1.19.4 | 1.19.4npm install @conform-to/dom@1.19.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @conform-to/dom, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @conform-to/dom to 1.19.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49250 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2026-49250 in your dependencies?
Find it across npm, including transitive dependencies.