# CVE-2026-21858: n8n Vulnerable to Unauthenticated File Access via Improper Webhook Request Handling

- Exploited (CISA KEV): no
- Published: 2026-01-07
- CVSS: 10 CRITICAL (v3.1)
- EPSS: 78.2% (100th percentile)
- CWE: CWE-20

n8n is an open source workflow automation platform. Versions starting with 1.65.0 and below 1.121.0 enable an attacker to access files on the underlying server through execution of certain form-based workflows. A vulnerable workflow could grant access to an unauthenticated remote attacker, resulting in exposure of sensitive information stored on the system and may enable further compromise depending on deployment configuration and workflow usage. This issue is fixed in version 1.121.0.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | No public claim | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2026-01-20 | 13 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### F5

- 2026-01-20 · new · rule 200020238
  > Added: signature 200020238 "n8n Remote Code Execution" (Malicious File Upload, risk High), systems: Other Web Server. References: CVE-2026-21858.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: passed (0 of 2 requests blocked), template CVE-2026-21858, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: passed (0 of 2 requests blocked), template CVE-2026-21858, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2026-21858 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2026-21858