CVE-2026-27191 — @feathersjs/authenticatio…
Fix: feathersjs/feathers@ee19a0aCVE-2026-27191 is a Open Redirect vulnerability in @feathersjs/authentication-oauth. A fix is available for @feathersjs/authentication-oauth — see the affected versions and patch details below.
Feathers: Open Redirect in OAuth callback enables account takeover
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-27191.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@feathersjs/authentication-oauthnpmDescription
Description
The redirect query parameter is appended to the base origin without validation, allowing attackers to steal access tokens via URL authority injection. This leads to full account takeover, as the attacker obtains the victim's access token and can impersonate them.
The application constructs the final redirect URL by concatenating the base origin with the user-supplied redirect parameter:
// https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/service.ts#L158C3-L176C4
const { redirect } = query;
...
session.redirect = redirect;
// https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/strategy.ts#L98
const redirectUrl = `${redirect}${queryRedirect}`;
Where:
redirect= base origin from config (e.g.,https://target.com)queryRedirect= user input from?redirect=parameter
This is exploitable when the origins array is configured and origin values do not end with /. An attacker can supply @attacker.com as the redirect value results in https://[email protected]#access_token=..., where the browser interprets attacker.com as the host, leading to full account takeover.
Credits: Abdelwahed Madani Yousfi (@vvxhid) / Edoardo Geraci (@b0-n0-b0) / Thomas Rinsma (@ThomasRinsma) From Codean Labs.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @feathersjs/authentication-oauth | all versions | 5.0.40npm install @feathersjs/authentication-oauth@5.0.40 |
Affected Products
feathersfeathersjsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @feathersjs/authentication-oauth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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-2026-27191 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Frequently Asked Questions
Is CVE-2026-27191 in your dependencies?
Find it across npm, including transitive dependencies.