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
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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-21877 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
n8nnpmDescription
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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | n8n | ≥ 0.123.0&&< 1.121.3 | 1.121.3npm install n8n@1.121.3 |
Detection & mitigation playbook
Open-source dependencyDetect
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-21877 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-21877. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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
Is CVE-2026-21877 in your dependencies?
O3 Security finds CVE-2026-21877 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.