CVE-2026-27493: n8n has Unauthenticated Expression Evaluation via Form Node

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.6%, percentile 76: FIRST’s model estimates a 1.6% chance of exploitation activity in the next 30 days, higher than 76% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes n8n (npm) < 1.123.22, fixed in 1.123.22; n8n (npm) >= 2.0.0, < 2.9.3, fixed in 2.9.3; n8n (npm) >= 2.10.0, < 2.10.1, fixed in 2.10.1. Check your lockfile, including transitive dependencies.

What it is

n8n is an open source workflow automation platform. Prior to versions 2.10.1, 2.9.3, and 1.123.22, 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. First, a form node with a field interpolating a value provided by an unauthenticated user, e.g. a form submitted value. Second, 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. 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. 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. 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 NODESEXCLUDE environment variable, and/or disable the Form Trigger node by adding n8n-nodes-base.formTrigger to the NODESEXCLUDE environment variable. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

From the GitHub advisory

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: = Thank you, {{ $input.first().json[\"Name\"] }}!

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.

Weakness type: CWE-94, CWE-95.

Product: n8n (npm) · Assigned by: GitHub_M · Published: 2026-02-25

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.61% probability of exploitation activity in the next 30 days; percentile 76.

Timeline

• 2026-02-25 — CVE record published by GitHub_M
• 2026-02-25 — GitHub-reviewed advisory GHSA-75g8-rv7v-32f7 published (critical)
• 2026-02-26 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-75g8-rv7v-32f7 github.com
2. CVE.org record CVE-2026-27493 cve.org
3. NVD entry CVE-2026-27493 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com
6. github.com github.com

Critical npm advisories · Today’s Security Digest