CVE-2026-40910
MEDIUMCVE-2026-40910 is a medium-severity (CVSS 6.5) Improper Authentication vulnerability in github.com/fatedier/frp. O3 Security confirms whether CVE-2026-40910 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
frp: Authentication bypass in frp HTTP vhost routing when routeByHTTPUser is used for access control
Real-World Exposure
github.com/fatedier/frpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
frp is a fast reverse proxy. From 0.43.0 to 0.68.0, frp contains an authentication bypass in the HTTP vhost routing path when routeByHTTPUser is used as part of access control. In proxy-style requests, the routing logic uses the username from Proxy-Authorization to select the routeByHTTPUser backend, while the access control check uses credentials from the regular Authorization header. As a result, an attacker who can reach the HTTP vhost entrypoint and knows or can guess the protected routeByHTTPUser value may access a backend protected by httpUser / httpPassword even with an incorrect Proxy-Authorization password. This issue affects deployments that explicitly use routeByHTTPUser. It does not affect ordinary HTTP proxies that do not use this feature. This vulnerability is fixed in 0.68.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fatedier/frp | ≥ 0.43.0&&< 0.68.1 | 0.68.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fatedier/frp. 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 github.com/fatedier/frp to 0.68.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40910 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-2026-40910 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-2026-40910. 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-2026-40910 in your dependencies?
O3 detects CVE-2026-40910 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.