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Graph/cross-subdomain-cookie-attribute-blocking

Pattern

Cross-Subdomain Cookie Misconfig

cross-subdomain-cookie-attribute-blocking

Session/JWT cookies fail to reach the expected frontend because cookie attributes (Domain, SameSite, HttpOnly, and framework placement) block browser storage, cross-site sending, or JavaScript access, breaking auth flows and redirect-based endpoints.

Node Details

Public graph metadata

Updated6/30/2026

Connections

30 linked nodes

Cookie “__vercel_live_token” has been rejected because it is in a cross-site context and its “SameSite” is “Lax” or “Strict” — deployed it on Vercel. Tension: But i setup cookies in my project like this. Outcome: Then you need to use https://localhost:5000 and not http://localhost:5000.

When the UI calls the `POST /auth/callback/passkey` endpoint. Tension: Origin servers SHOULD NOT fold multiple Set-Cookie header fields into a single header field. Outcome: Cloudflare seem to be in the wrong here.

when I refresh my page the cookie gets deleted — I have deployed my sveltekit frontend and python flask backend on vercel. Tension: On localhost, they worked just fine however when I deployed it, the cookies were not persistent. Outcome: it does sets the cookie, but on refresh, the cookie gets disappeared.

django.security.csrf: Forbidden (Origin checking failed - https://sentry-domain.com does not match any trusted origins.) — /account/recover/ (status_code=403 request=<WSGIRequest: POST '/account/recover/'>). Tension: when it comes to login (correct or wrong username and password). Outcome: It is solved by some steps.

Using Fetch from my `index.html` from my `portal.mydomain.com` does not. — Enter `api.mydomain.com` into a browser directly does save my cookie. Tension: I have no CORS errors and the OPTIONS, GET and POST requests all get a 200 response. Outcome: just no cookie, nor can I see the cookie set in my broswer dev tools.

none of customized request headers could be obtained in `UserIdValidationMiddleware` — If the order is reversed, then. Tension: It is not on the axios side. Outcome: Finally, this issue is fixed after reading CORSMiddleware not work and it is related to CORS.

RedirectResponse goes to "/" without the authentication cookie

AADSTS9002325: Proof Key for Code Exchange is required for cross-origin authorization code redemption. Tension: redirects uris not matching.

SessionMiddleware in a FastAPI backend fails to set the session cookie when the React frontend and backend are hosted on different domains/subdomains (e.g., XXX-ui.fly.dev vs XXX-api.fly.dev). The browser rejects the cookie with an 'invalid domain' error and no session is maintained.

were not accessible in js and in browser — Cookies are being set and sent with the next request. Outcome: The problem solved by adding `domain="blueberry.adefe.xyz"` to the cookie in response.

FastAPI returns 401 with JWK public Attribute for authorization token not found

MissingKeyMissing Key-Pair-Id query parameter or cookie value — {urn}/manifest/{derivativeurn}/signedcookies. Tension: I get the following error that suggest I'm missing a header.

Embedding a CPQ web app as an iframe inside Salesforce fails to persist authentication cookies/session for API calls. Login in a new tab isn’t recognized inside the Salesforce iframe, preventing authorized requests.

the cookie will be specifically set with `domain=app.sunsetland.com.au`. Tension: if we were to host another subdomain aside from `app.`, we actually would likely encounter the reCAPTCHA challenge again.

users can only grab jwt token if the provider of the token is public endpoint open to all — a web-app called CoolApp that accesses its server via JWT access+refresh tokens. Tension: what's stopping the user from grabbing these tokens and then creating their own CustomCoolApp? Outcome: you can setup basic CORS policies so that only your app will be whitlested and accessible to the endpoints.

can I create, from 2. and 3. a server side httpOnly cookie (containing a `widget_id`) of domain `mycompany-example.com`, that can be used during step 5. Outcome: when the user visits our website so we know which widget they come from ?

Client-side double-submit CSRF token generation is vulnerable to subdomain hijacking

Confusion about cookie authentication versus token authentication

it is also required to "forget" the token right after exiting/closing the app — I have a web API which uses JWT tokens for accessing resources. Tension: The issue with (1) is that it's not cleared when a browser's tab is closed but only when all the windows are. And (2) is not secure since if an attacker manages to inject a code into a client he will be able to extract the access token.

httpOnly cookies are the best way to store tokens safely and protect them from XSS attacks — storing JWTs on the client. Tension: JavaScript won't be allowed to read httpOnly cookies. How would the client handle routes authentication? Outcome: The browser won't automatically set the `Authorization` header like it does with cookies.

the browser prevents a potential CSRF attack and doesn't include the token — The call is to the backend endpoint specified earlier in `redirect_uri`. Tension: I need a browser to include the `ASP.NET_SessionId` cookie in the request. Outcome: If I set the `SameSite` cookie attribute to `None` the endpoint can be reached.

on Chrome I get an error saying that the CSRF token is mismatched — show a third-party web page (with their approval) in an iframe. Tension: This site has a different domain to my parent site. Outcome: The site displays fine on firefox.

If I check 'Remember Me' in form, this add a cookie with name "REMEMBERME". Tension: I'm implementing custom authenticator. Outcome: your cookie is normal.

Fortify SCA reports that the following code is DOM XSS vulnerable — const returnUrl = sessionStorage.getItem('returnUrl') || '/'; window.location.href = returnUrl;. Outcome: Don't store a full URL, just store the necessary information.

The session identifier (req.sessionID) changed on every subsequent HTTP request from the React client to the Express server, preventing consistent session persistence.

req.cookies.jwt is defined in localhost but undefined in deployment — The cookies are being set in the browser. Tension: the only problem is I can't access them. Outcome: Here to ken is undefined.

The browser does not store the refresh token cookie returned by the Django Ninja login endpoint, even though the cookie appears in the response headers and the fetch call uses credentials: 'include'.

one is working without any credential or cookie[SessionId] but another one is not working — two api's in my spring mvc project which have identical structure. Tension: while calling using Postman or while hitting the APIs in browser/UI project.

Wget before 1.21.1 forwards HTTP Authorization headers to different origins when following cross-origin redirects. — when following cross-origin redirects. Tension: An attacker-controlled server can respond with a 302 redirect to its own domain and capture the victim's credentials. Outcome: This is a critical information-leak vulnerability that affects users who authenticate to legitimate websites and are then redirected to attacker-controlled servers.

throws "Cookies can only be modified in a Server Action or Route Handler" — called from Next.js 15 Server Components (pages, layouts). Tension: The error appears intermittently — only when the session needs refreshing (controlled by `updateAge` config). Outcome: With `updateAge: 300` (5 minutes), it crashes every ~5 minutes for active users.

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