CVE-2026-39371
HIGHRedwoodSDK is a server-first React framework. From 1.0.0-beta.50 to 1.0.5, erver functions exported from "use server" files could be invoked via GET requests, bypassing their intended…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
RedwoodSDK is a server-first React framework. From 1.0.0-beta.50 to 1.0.5, erver 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. This vulnerability is fixed in 1.0.6.
Affected Products
redwoodsdkredwoodjsDetection & mitigation playbook
Vendor / applianceDetect
Inventory every redwoodjs redwoodsdk deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the redwoodjs redwoodsdk security patch or hotfix for CVE-2026-39371 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-39371 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-39371. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-39371 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-39371 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.