CVE-2026-24687 — Umbraco.Forms
CVE-2026-24687 is a security vulnerability in Umbraco.Forms. A fix is available for Umbraco.Forms — see the affected versions and patch details below.
Umbraco.Forms has Path Traversal and File Enumeration Vulnerabilities in Linux/Mac
Exploitation Status
No confirmed exploitation observed yet
- 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-2026-24687.
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.
Real-World Exposure
Umbraco.Forms.NETUmbraco.FormsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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.
Patches
This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1
Workarounds
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 thefileNameparameter of the export endpoint - Restricting network access to the Umbraco backoffice to trusted IP ranges
- Blocking the
/umbraco/forms/api/v1/exportendpoint entirely if the export feature is not required
However, upgrading to the patched version is strongly recommended.
References
Credit to Kevin Joensen from Baldur Security for finding this vulnerability
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Umbraco.Forms | ≥ 16.0.0&&< 16.4.1 | 16.4.1dotnet add package Umbraco.Forms --version 16.4.1 |
| .NETNuGet | Umbraco.Forms | ≥ 17.0.0&&< 17.1.1 | 17.1.1dotnet add package Umbraco.Forms --version 17.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Umbraco.Forms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Umbraco.Forms to 16.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-24687 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-24687 can be triaged on real exposure rather than presence alone.
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 in your dependencies?
O3 Security finds CVE-2026-24687 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.