CVE-2026-86081: n8n: Regular Expression Denial of Service in the Default Blocked-File-Pattern Match via a Git Node Clone Path

The default N8N_BLOCK_FILE_PATTERNS expression was written in a way that a crafted path makes the regex engine backtrack heavily. The check runs synchronously in the main n8n process, so while it spins nothing else is served: the editor, webhooks, scheduled runs and API calls all stall for every user.

The attacker needs an account that can run a workflow with a Git node set to clone to a crafted destination path. No unusual configuration is needed, since the vulnerable pattern is the default. The CVSS 4.0 vector shows availability impact only. The patch rewrites the pattern so matching is linear in the path length.

For teams that share one n8n instance, a single member, or a compromised member account, can take down automation for the rest. A restart clears the freeze, but the user can repeat it.

Affected: n8n before 1.123.76; 2.0.0 up to but not including 2.37.7; and 2.38.0 and 2.38.1. It applies to instances that still use the default N8N_BLOCK_FILE_PATTERNS, with the Git node available. Check:

n8n --version

For Docker, check the image tag.

Upgrade to n8n 1.123.76, 2.37.7 or 2.38.2, or later.

npm install -g [email protected]

n8n's interim mitigations: restrict instance access to fully trusted users, disable the Git node by adding n8n-nodes-base.git to NODES_EXCLUDE, or set N8N_BLOCK_FILE_PATTERNS to a backtracking-safe equivalent. These do not fully remediate the risk.

Look for the n8n process pinned at full CPU on one core with the UI and webhooks unresponsive, followed by a restart. Check execution history for runs of a Git node with the clone operation and an unusually long or repetitive destination path, started just before the stall. Identify the user who ran that workflow.

Impact

The Git node's clone operation matched the destination path against the default N8N_BLOCK_FILE_PATTERNS expression, which was written so that a crafted path caused catastrophic backtracking. Evaluation runs synchronously in the main n8n process, so an authenticated user could freeze the instance for everyone with a single workflow execution and no unusual configuration. The patch rewrites the pattern so that matching is linear in the length of the path.

Patches

The issue has been fixed in n8n versions 1.123.76, 2.37.7, and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators should consider the following temporary mitigations:

• Restrict n8n instance access to fully trusted users only.
• Disable the Git node by adding n8n-nodes-base.git to the NODES_EXCLUDE environment variable.
• Set N8N_BLOCK_FILE_PATTERNS to a backtracking-safe equivalent pattern to replace the vulnerable default.

These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.