CVE-2026-33720: n8n Has Authorization Bypass in OAuth Callback via N8N_SKIP_AUTH_ON_OAUTH_CALLBACK
Impact When the N8NSKIPAUTHONOAUTHCALLBACK environment variable is set to true, the OAuth callback handler skips ownership verification of the OAuth state parameter. This allows an attacker to trick a victim into completing an OAuth flow against a credential object the attacker controls, causing the victim's OAuth tokens to be stored in the attacker's credential. The attacker can then use those tokens to execute workflows in their name.
- This issue only affects instances where N8NSKIPAUTHONOAUTHCALLBACK=true is explicitly configured (non-default).
Patches The issue has been fixed in n8n version 2.8.0. Users should upgrade to this version or later to remediate the vulnerability.
Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Avoid enabling N8NSKIPAUTHONOAUTHCALLBACK=true unless strictly required. - Restrict access to the n8n instance to fully trusted users only.
These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
Other sources
n8n is an open source workflow automation platform. Prior to version 2.8.0, when the N8NSKIPAUTHONOAUTHCALLBACK environment variable is set to true, the OAuth callback handler skips ownership verification of the OAuth state parameter. This allows an attacker to trick a victim into completing an OAuth flow against a credential object the attacker controls, causing the victim's OAuth tokens to be stored in the attacker's credential. The attacker can then use those tokens to execute workflows in their name. This issue only affects instances where N8NSKIPAUTHONOAUTHCALLBACK=true is explicitly configured (non-default). The issue has been fixed in n8n version 2.8.0. Users should upgrade to this version or later to remediate the vulnerability. If upgrading is not immediately possible, administrators should consider the following temporary mitigations: Avoid enabling N8NSKIPAUTHONOAUTHCALLBACK=true unless strictly required, and/ or restrict access to the n8n instance to fully trusted users only. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33720?
CVE-2026-33720 has been classified as a high severity vulnerability due to the potential for unauthorized access.
How do I fix CVE-2026-33720?
To fix CVE-2026-33720, upgrade n8n to version 2.8.0 or later to ensure proper authorization checks are in place.
What does CVE-2026-33720 affect?
CVE-2026-33720 affects versions of n8n prior to 2.8.0 when the N8N_SKIP_AUTH_ON_OAUTH_CALLBACK variable is set to true.
How does CVE-2026-33720 impact n8n users?
CVE-2026-33720 allows attackers to bypass authorization during OAuth callbacks, potentially compromising user data.
What is the N8N_SKIP_AUTH_ON_OAUTH_CALLBACK environment variable?
The N8N_SKIP_AUTH_ON_OAUTH_CALLBACK environment variable, when set to true, disables ownership verification for OAuth callbacks, leading to possible unauthorized access.