How severe is CVE-2026-21877?

CVE-2026-21877 has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-21877?

CVE-2026-21877 affects the following packages: n8n (npm). Ecosystems affected: npm.

How do I fix CVE-2026-21877?

Update n8n to 1.121.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-21877 is resolved across your whole dependency graph.

How do I detect CVE-2026-21877 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for n8n, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-21877 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-21877 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-21877 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-21877?

CVE-2026-21877 has an EPSS (Exploit Prediction Scoring System) score of 5.4%, placing it in the 93th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-21877?

CVE-2026-21877 is classified as Code Injection (CWE-94), Unrestricted File Upload (CWE-434). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Is there exploit tooling available for CVE-2026-21877?

A Nuclei detection template exists for CVE-2026-21877, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2026-21877 published, and has it been updated?

CVE-2026-21877 was published on January 8, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

CRITICAL severity

CVE-2026-21877 — n8n

CRITICALFix: n8n-io/n8n@f4b009d

CVE-2026-21877 is a critical-severity (CVSS 9.9) Code Injection vulnerability in n8n. A fix is available for n8n — see the affected versions and patch details below.

n8n is vulnerable to Remote Code Execution via Arbitrary File Write

Also known asGHSA-v364-rw7m-3263

Published

Jan 8, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-21877.

EPSS Exploitation Probability

via FIRST.org ↗

5.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

36other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

n8nnpm

160Kdownloads / week

Description

Impact

n8n is affected by an authenticated Remote Code Execution (RCE) vulnerability.

Under certain conditions, an authenticated user may be able to cause untrusted code to be executed by the n8n service. This could result in full compromise of the affected instance.

Both self-hosted and n8n Cloud instances are impacted.

Patches

The issue has been resolved in n8n version 1.121.3.

Users are advised to upgrade to this version or later to fully address the vulnerability.

Workarounds

If upgrading is not immediately possible, administrators can reduce exposure by disabling the Git node and limiting access for untrusted users.

References

n8n documentation: Blocking access to nodes

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`n8n`	≥ 0.123.0&&< 1.121.3	1.121.3`npm install n8n@1.121.3`

Affected Products

1 product · 1 configurations

Application

n8nn8n

≥ 0.123.0 && < 1.121.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for n8n, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update n8n to 1.121.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-21877 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

How to detect CVE-2026-21877

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2026-21877 -u https://target

Template: n8n >= 0.123.0 and < 1.121.3 - Remote Code Execution
Severity: critical
Impact: Full system compromise including access to all credentials, API tokens, OAuth secrets, database connections, and workflow automation capabilities. n8n becomes a single point of failure exposing all connected systems.
Remediation: Upgrade to n8n v1.121.3 or later. If upgrading is not immediately possible, disable the Git node and limit access for untrusted users.

Template by ProjectDiscovery nuclei-templates (s4e-io), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

### Impact n8n is affected by an authenticated Remote Code Execution (RCE) vulnerability. Under certain conditions, an authenticated user may be able to cause untrusted code to be executed by the n8n service. This could result in full compromise of the affected instance. Both self-hosted and n8n Cloud instances are impacted. ### Patches The issue has been resolved in n8n version 1.121.3. Users are advised to upgrade to this version or later to fully address the vulnerability. ### Workarounds If upgrading is not immediately possible, administrators can reduce exposure by disabling the Git