CVE-2026-39371 — rwsdk
HIGHCVE-2026-39371 is a high-severity (CVSS 8.1) Cross-Site Request Forgery (CSRF) vulnerability in rwsdk. A fix is available for rwsdk — see the affected versions and patch details below.
RedwoodSDK has a CSRF vulnerability in server function dispatch via GET requests
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-39371.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
rwsdknpmDescription
Summary
Server functions exported from "use server" files could be invoked via GET requests, bypassing their intended HTTP method. In cookie-authenticated applications, this allowed cross-site GET navigations to trigger state-changing functions, because browsers send SameSite=Lax cookies on top-level GET requests.
This affected all server functions -- both serverAction() handlers and bare exported functions in "use server" files.
Impact
An attacker could construct a URL containing a known action ID and JSON-encoded arguments. When a victim with an active session visited or was redirected to this URL, the function executed with the victim's credentials. This affected any server function that performs state-changing operations (writes, deletes, mutations) in applications using cookie-based authentication.
Remediation
Update to rwsdk 1.0.6. No application code changes are required.
The fix enforces the declared HTTP method at dispatch time. GET requests to server functions that require POST now return 405 Method Not Allowed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | rwsdk | ≥ 1.0.0-beta.50&&< 1.0.6 | 1.0.6npm install rwsdk@1.0.6 |
Affected Products
redwoodsdkredwoodjsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rwsdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rwsdk to 1.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39371 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-2026-39371 in your dependencies?
Find it across npm, including transitive dependencies.