CVE-2026-24687
MEDIUMUmbraco Forms is a form builder that integrates with the Umbraco content management system. It's possible for an authenticated backoffice-user to enumerate and traverse paths/files…
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
Umbraco Forms is a form builder that integrates with the Umbraco content management system. It's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected. This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1. If upgrading is not immediately possible, users can mitigate this vulnerability by configuring a WAF or reverse proxy to block requests containing path traversal sequences (../, ..\) in the fileName parameter of the export endpoint, restricting network access to the Umbraco backoffice to trusted IP ranges, and/or blocking the /umbraco/forms/api/v1/export endpoint entirely if the export feature is not required. However, upgrading to the patched version is strongly recommended.
Affected Products
umbraco formsumbracoDetection & mitigation playbook
Vendor / applianceDetect
Inventory every umbraco umbraco forms 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 umbraco umbraco forms security patch or hotfix for CVE-2026-24687 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-2026-24687 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-2026-24687. 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-2026-24687 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-24687 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.