CVE-2026-27192
Feathers has an origin validation bypass via prefix matching
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.
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@feathersjs/authentication-oauthnpmDescription
Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In versions 5.0.39 and below, origin validation uses startsWith() for comparison, allowing attackers to bypass the check by registering a domain that shares a common prefix with an allowed origin.The getAllowedOrigin() function checks if the Referer header starts with any allowed origin, and this comparison is insufficient as it only validates the prefix. This is exploitable when the origins array is configured and an attacker registers a domain starting with an allowed origin string (e.g., https://target.com.attacker.com bypasses https://target.com). On its own, tokens are still redirected to a configured origin. However, in specific scenarios an attacker can initiate the OAuth flow from an unauthorized origin and exfiltrate tokens, achieving full account takeover. This issue has bee fixed in version 5.0.40.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @feathersjs/authentication-oauth | all versions | 5.0.40 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @feathersjs/authentication-oauth. 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 @feathersjs/authentication-oauth to 5.0.40 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-27192 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-2026-27192 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-2026-27192. 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-2026-27192 in your dependencies?
O3 detects CVE-2026-27192 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.