CVE-2026-81890 is a medium-severity (CVSS 5.4) Cross-Site Request Forgery (CSRF) vulnerability in studio-42/elfinder. O3 Security confirms whether CVE-2026-81890 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
elFinder: CSRF in netmount allows forced FTP mounts and server-side FTP connections
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-81890.
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.
How urgent is this, really
CVE-2026-81890 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 367,633 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
studio-42/elfinderReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
elFinder is an open-source file manager for web, written in JavaScript using jQuery UI. Prior to 2.1.70, the netmount command is omitted from elFinderConnector::$csrfProtectedCmds in php/elFinderConnector.class.php, so validateCsrfToken() is not called for this state-changing operation. In the shipped php/connector.minimal.php-dist configuration, FTP network mounts are enabled by default, and attacker-controlled protocol, host, path, port, user, pass, alias, and options arguments flow through elFinder::netmount() in php/elFinder.class.php to php/elFinderVolumeFTP.class.php. A cross-site request can therefore persist an attacker-chosen FTP mount in the victim's session, cause the PHP server to connect to an attacker-chosen FTP host and port, and send supplied credentials without an X-elFinder-CSRF token. This issue is fixed in version 2.1.70.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | studio-42/elfinder | all versions | 2.1.70 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for studio-42/elfinder. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update studio-42/elfinder to 2.1.70 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-81890 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 pinpoints whether CVE-2026-81890 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-81890. 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-2026-81890 in your dependencies?
O3 detects CVE-2026-81890 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.