#oauth

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL.

### Impact All deployments of OAuth2 Proxy in front of applications that normalize underscores to dashes in HTTP headers (e.g., WSGI-based frameworks such as Django, Flask, FastAPI, and PHP applications). Authenticated users can inject underscore variants of X-Forwarded-* headers that bypass the proxy’s filtering logic, potentially escalating privileges in the upstream app. OAuth2 Proxy authentication/authorization itself is not compromised. ### Patches This change mitigates a request header smuggling vulnerability where an attacker could bypass header stripping by using different capitalization or replacing dashes with underscores. The problem has been patched with v7.13.0. By default all specified headers will now be normalized, meaning that both capitalization and the use of underscores (_) versus dashes (-) will be ignored when matching headers to be stripped. For example, both `X-Forwarded-For` and `X_Forwarded-for` will now be treated as equivalent and stripped away. However...

### Summary If the "claims_parameter_supported" parameter is activated, it is possible through the "oidc-claims-extension.groovy" script, to inject the value of choice into a claim contained in the id_token or in the user_info. Authorization function requests do not prevent a claims parameter containing a JSON file to be injected. This JSON file allows users to customize claims returned by the "id_token" and "user_info" files. This allows for a very wide range of vulnerabilities depending on how clients use claims. For example, if some clients rely on an email field to identify a user, users can choose to entera any email address, and therefore assume any chosen identity.

Active Directory remains the authentication backbone for over 90% of Fortune 1000 companies. AD's importance has grown as companies adopt hybrid and cloud infrastructure, but so has its complexity. Every application, user, and device traces back to AD for authentication and authorization, making it the ultimate target. For attackers, it represents the holy grail: compromise Active

### Summary _Short summary of the problem. Make the impact and severity as clear as possible. A flawed implementation of the Kubernetes aggregation layer's authentication flow could enable bypassing RBAC controls. ### Details _Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer._ It was discovered that the `virt-api` component fails to correctly authenticate the client when receiving API requests over mTLS. In particular, it fails to validate the CN (Common Name) field in the received client TLS certificates against the set of allowed values defined in the `extension-apiserver-authentication` configmap. The Kubernetes API server proxies received client requests through a component called aggregator (part of K8S's API server), and authenticates to the `virt-api` server using a certificate signed by the CA specified via the `--requestheader-client-ca-file` CLI flag. This CA bundle is primarily used in the context of aggr...

Authentication Bypass Using an Alternate Path or Channel vulnerability in Drupal Simple OAuth (OAuth2) & OpenID Connect allows Authentication Bypass. This issue affects Simple OAuth (OAuth2) & OpenID Connect: from 6.0.0 before 6.0.7.

### Summary While setting up an oauth client, it was noticed that the callback page hosted by the client during the flow embeds user-controlled content without escaping or sanitizing it. This leads to a reflected Cross-Site-Scripting vulnerability. ### Details The affected code is located in *https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/oauth_callback.py*, which embeds all values passed to the `create_callback_html` function via the `message` parameter it into the callback page without escaping them. This can, for example, be abused by calling the callback server with an XSS payload inside the `error` GET parameter, the value of which will then be inserted into the callback page, causing the execution of attacker-controlled JavaScript code in the callback server's origin. Note that besides the `error` parameter, other parameters reaching this function are affected too. ### PoC 1. Setup a simple fastmcp client such as this one (the callback server's port was fixated ...

### Summary FastMCP documentation [covers the scenario](https://gofastmcp.com/integrations/azure) where it is possible to use Entra ID or other providers for authentication. In this context, because Entra ID does not support Dynamic Client Registration (DCR), the FastMCP-hosted MCP server is acting as the authorization provider, as declared in the Protected Resource Metadata (PRM) document hosted on the server. For example, on a local MCP server, it may be hosted here: ```http http://localhost:8000/.well-known/oauth-protected-resource ``` And the JSON representation of the PRM document: ```json { "resource": "http://localhost:8000/mcp", "authorization_servers": [ "http://localhost:8000/" ], "scopes_supported": [ "User.Read", "email", "openid", "profile" ], "bearer_methods_supported": [ "header" ] } ``` Notice that the `authorization_servers` field contains the MCP server itself - it acts as an **OAuth Client** to the downstream authorization ...

The New Reality for Lean Security Teams If you’re the first security or IT hire at a fast-growing startup, you’ve likely inherited a mandate that’s both simple and maddeningly complex: secure the business without slowing it down. Most organizations using Google Workspace start with an environment built for collaboration, not resilience. Shared drives, permissive settings, and constant

Security, trust, and stability — once the pillars of our digital world — are now the tools attackers turn against us. From stolen accounts to fake job offers, cybercriminals keep finding new ways to exploit both system flaws and human behavior. Each new breach proves a harsh truth: in cybersecurity, feeling safe can be far more dangerous than being alert. Here’s how that false sense of security