OAuth

Flowise v3.1.2 and earlier are vulnerable to unauthenticated remote code execution because the CVE-2025-8943 patch relies on an incomplete environment variable blocklist, allowing attackers to inject configuration variables that force arbitrary package installation.

The better-auth library fails to validate redirect_uri schemes in its oidc-provider and mcp plugins, allowing attackers to inject javascript: URIs that lead to XSS and potential account takeover.

MaxKey versions through 4.1.12 are vulnerable to OAuth 2.0 authorization code hijacking due to improper host boundary checks in the DefaultRedirectResolver component.

The 'oauth' Ruby gem versions 0.5.5 through 1.1.5 are vulnerable to a critical issue (CVE-2026-54605) where the 'OAuth::Consumer#token_request' method improperly handles HTTP 3xx redirects during OAuth 1.0 token exchanges, enabling an attacker to redirect the request to a malicious host, exposing sensitive OAuth 1.0 metadata, and facilitating Server-Side Request Forgery (SSRF) and confused-deputy behavior.

An authorization bypass vulnerability (CVE-2026-55502) in Cloudreve 4.16.1 allows an attacker with an `Admin.Read` OAuth token to modify the OneDrive storage policy credentials via a POST request to `/api/v4/admin/policy/oauth/signin`, despite lacking `Admin.Write` scope, which can break the storage backend and redirect future OAuth setups.

An improper authorization vulnerability in Gitea's OAuth2 sign-in callback mechanism (CVE-2026-58422) allows users with linked external identity providers to unilaterally re-enable their administrator-disabled accounts, regaining full access and bypassing security controls.

Cloudreve's OAuth implementation contains a vulnerability, CVE-2026-54560, where OAuth access tokens bypass intended scope enforcement due to a missing `client_id` claim, allowing an attacker with a low-scope token to access sensitive APIs requiring higher privileges, effectively leading to privilege escalation.

A third-party marketing vendor, Klue, experienced unauthorized access to its integration layer, which connects to other SaaS platforms like Salesforce, leading to the compromise of an OAuth token and subsequent unauthorized access to Recorded Future's Salesforce account, where business data fields including customer contact names, email addresses, and potentially business contract information were accessed.

An unvalidated redirect vulnerability, CVE-2026-54072, in the Authorizer `/authorize` endpoint allows an unauthenticated attacker to steal OAuth2 access, ID, and refresh tokens by crafting a malicious URL with an attacker-controlled `redirect_uri` to which the application redirects a logged-in user, exposing their tokens.

The legacy `oidcProvider` and `mcp` plugins in the `better-auth` library versions prior to 1.6.11 are vulnerable to CVE-2026-53512, an OAuth refresh-token replay attack where the plugins fail to verify the `client_secret` of confidential clients during the `refresh_token` grant, allowing an attacker who obtains a valid `refresh_token` and `client_id` to indefinitely mint new access tokens and impersonate the client for unauthorized resource access.

Detects Microsoft Entra ID sign-in activity where the Microsoft Authentication Broker requests the Device Registration Service from a suspicious ASN, indicating potential OAuth phishing or adversary-in-the-middle device registration.

The Red Canary Intelligence Insights report for May 2026 highlights the rise of ClearFake, ACR Stealer, and GraphRunner, with ClearFake using JavaScript injection to deliver malware like ACR Stealer, and GraphRunner being abused for reconnaissance and data exfiltration via the Microsoft Graph API.

This rule detects potential session hijacking or token replay in Microsoft Entra ID, identifying cases where a user signs in and subsequently accesses Microsoft Graph from a different IP address using the same session ID, which may indicate a successful OAuth phishing attack, session hijacking, or token replay attack.

The mcp-security framework fails to implement SSRF mitigations outlined in the Model Context Protocol, processing untrusted URLs for OAuth-related discovery and metadata without verification, affecting installations with Dynamic Client Registration (DCR) enabled and exposing them to potential Server-Side Request Forgery (SSRF) attacks, tracked as CVE-2026-45609.

The Tycoon2FA phishing kit now supports device-code phishing attacks targeting Microsoft 365 accounts, abusing Trustifi click-tracking URLs, redirecting victims through Cloudflare Workers to a fake Microsoft CAPTCHA page, tricking them into entering a device code, and granting attackers OAuth tokens and access to their Microsoft 365 accounts.

Open WebUI is vulnerable to stored cross-site scripting (XSS) via OAuth profile picture handling, allowing an attacker to inject malicious SVG code and potentially takeover user accounts by exfiltrating JWT tokens.

CVE-2026-45732 describes a high-severity authorization bypass vulnerability in n8n's OAuth1 and OAuth2 credential reconnect endpoints, where insufficient permission checks allow a user with read-only access to overwrite OAuth tokens, potentially leading to data exfiltration and persistent takeover of shared integrations.

Threat actors are increasingly using device code phishing, often via Phishing-as-a-Service platforms, to compromise user accounts by abusing the OAuth 2.0 device authorization grant flow and capturing authentication tokens, enabling account takeover, data theft, and business email compromise.

The MonsterInsights WordPress plugin through 10.1.2 is vulnerable to unauthorized access and data modification, allowing authenticated attackers with subscriber-level access to retrieve Google OAuth tokens and reset Google Ads integration due to missing capability checks on `get_ads_access_token()` and `reset_experience()` functions.

Attackers can silently redirect Claude Code MCP traffic to intercept OAuth tokens, enabling persistent access to connected SaaS platforms by modifying the ~/.claude.json file in a man-in-the-middle attack.

phpMyFAQ is vulnerable to SQL injection due to the `setTokenData` function failing to sanitize OAuth token fields from Azure AD JWT claims, potentially allowing attackers to execute arbitrary SQL commands via crafted Azure AD display names or custom claims.

n8n is vulnerable to cross-site scripting (XSS) via a malicious MCP OAuth client, allowing an unauthenticated attacker to inject arbitrary JavaScript into an authenticated user's session.

In early April 2026, Arctic Wolf tracked a large-scale device code phishing campaign across multiple regions and sectors where threat actors abused OAuth device code flow to trick victims into providing authentication codes.

An authorization bypass vulnerability exists in Better Auth's OAuth provider, allowing low-privilege users to create OAuth clients despite configured clientPrivileges, potentially leading to unauthorized client registration and increased phishing risks.

Detects suspicious OAuth 2.0 token requests where the Microsoft Authentication Broker requests access to the Device Registration Service on behalf of a user principal, potentially indicating an attempt to abuse device registration for unauthorized persistence.

A phishing campaign abuses Microsoft's Device Code OAuth flow to gain access to cloud-based file storage and document workflow platforms, bypassing traditional credential harvesting.

Detects a sequence of events where a user copies a Google Workspace object (spreadsheet, form, document, or script) from an external drive and subsequently grants OAuth permissions to a custom application, potentially indicating a phishing attack leveraging container-bound scripts.

Attackers are leveraging device code phishing to steal application access tokens from users of Entra ID OAuth applications, by tricking users into entering codes into attacker-controlled polling clients, leading to unauthorized access to cloud resources.

Ech0's OAuth redirect URI validation ignores the path component, allowing attackers to craft malicious redirect URIs for exchange-code theft and potential account takeover.

Detects anomalous access to email resources via Microsoft Graph API, potentially indicating a compromised OAuth refresh token or Primary Refresh Token (PRT) being used by an attacker.

Attackers are leveraging first-party Microsoft applications in Entra ID to conduct OAuth phishing attacks, bypassing traditional consent prompts and accessing sensitive resources like Microsoft Graph and legacy Azure AD.

Attackers register malicious applications within Entra ID and deceive users into granting extensive permissions through OAuth consent, enabling unauthorized access to sensitive data like emails and files.

Adversaries with stolen credentials or OAuth tokens may abuse Entra ID-managed or first-party client IDs to perform on-behalf-of (OBO) authentication, blending into legitimate cloud traffic and evading detection by using a rare application ID for principal authentication.

Detects potential session hijacking or token replay in Microsoft Entra ID, where a user signs in and subsequently accesses Microsoft Graph from a different IP address using the same session ID, indicating a successful OAuth phishing attack, session hijacking, or token replay attack.

The Patreon OAuth provider in go-pkgz/auth and go-pkgz/auth/v2 maps every authenticated Patreon account to the same local user ID, leading to cross-account access, privilege confusion, and subscription-state leakage.

The disabling of the 'risk-based step-up consent' security setting in Microsoft 365 allows users to grant consent to potentially malicious applications, increasing the risk of OAuth phishing and unauthorized access to sensitive data.

Nhost is vulnerable to account takeover due to improper OAuth email verification in Discord, Bitbucket, AzureAD, and EntraID providers, allowing attackers to merge an unverified OAuth identity into a victim's account.

The Microsoft 365 'risk-based step-up consent' security setting is disabled by an adversary to allow users to grant consent to malicious applications, potentially leading to unauthorized access and data breaches.

Adversaries may register a malicious application in Microsoft Entra ID and trick users into granting excessive permissions via OAuth consent, allowing the malicious application to access resources in Microsoft 365 on behalf of the user, potentially leading to data exfiltration.

An application accessing SharePoint Online or OneDrive for Business for the first time in a tenant could indicate OAuth phishing, illicit consent grants, or compromised third-party apps accessing file storage.

Adversaries may abuse the user_impersonation OAuth scope in Entra ID to gain unauthorized access to user accounts, especially when combined with single-factor authentication and unbound sign-in sessions, potentially indicating account compromise for users not seen in the last 10 days.

Detects the first-time use of an OAuth 2.0 authorization code grant flow for a specific combination of user, application, and resource in Microsoft Entra ID, potentially indicating OAuth phishing attacks like ConsentFix, where attackers steal authorization codes.

Azure AD blocked a user's attempt to grant consent to a risky application, indicating potential OAuth abuse and requiring investigation of the user and application involved.

The analytic detects when the risk-based step-up consent security setting in Azure AD is disabled by monitoring Azure Active Directory logs for the 'Update authorization policy' operation and changes to the 'AllowUserConsentForRiskyApps' setting, potentially exposing organizations to OAuth phishing attacks.

Detection of Azure AD OAuth application consent granted by a user, potentially leading to unauthorized access and data compromise.

An adversary might use a phished OAuth refresh token or Primary Refresh Token (PRT) with a first-party application to access email resources via Microsoft Graph API, particularly focusing on unusual application and user combinations.

This analytic identifies instances where a user has denied consent to an OAuth application seeking permissions within the Azure AD environment, potentially indicating malicious OAuth application activity.