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GHSA-75g8-rv7v-32f7

CriticalCVSS 9 / 10
Published Feb 25, 2026·Last modified Feb 28, 2026
Affected Components(0)

No affected components available

Description

Impact

A second-order expression injection vulnerability existed in n8n's Form nodes that could allow an unauthenticated attacker to inject and evaluate arbitrary n8n expressions by submitting crafted form data. When chained with an expression sandbox escape, this could escalate to remote code execution on the n8n host.

The vulnerability requires a specific workflow configuration to be exploitable:

  1. A form node with a field interpolating a value provided by an unauthenticated user, e.g. a form submitted value.
  2. The field value must begin with an = character, which caused n8n to treat it as an expression and triggered a double-evaluation of the field content. For example, a workflow uses a multi-step Form where a downstream Form node renders user-provided input back in an HTML field and precedes it with an = sign: =<h2>Thank you, {{ $input.first().json[\"Name\"] }}!</h2>

There is no practical reason for a workflow designer to prefix a field with = intentionally — the character is not rendered in the output, so the result would not match the designer's expectations. If added accidentally, it would be noticeable and very unlikely to persist. An unauthenticated attacker would need to either know about this specific circumstance on a target instance or discover a matching form by chance.

Even when the preconditions are met, the expression injection alone is limited to data accessible within the n8n expression context. Escalation to remote code execution requires chaining with a separate sandbox escape vulnerability.

Due to these real-world constraints — the unlikely workflow configuration, the need for an additional sandbox escape, and the difficulty of discovery — we have assessed the severity as High rather than Critical, diverging from the base CVSS score to better reflect actual exploitability.

Patches

The issue has been fixed in n8n versions 2.10.1, 2.9.3, and 1.123.22. 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:

  • Review usage of form nodes manually for above mentioned preconditions.
  • Disable the Form node by adding n8n-nodes-base.form to the NODES_EXCLUDE environment variable.
  • Disable the Form Trigger node by adding n8n-nodes-base.formTrigger to the NODES_EXCLUDE environment variable.

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

Risk Scores
Base Score
9.0

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
8.2

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
1.07%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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