# CVE-2026-12940: Langflow is affected by remote code execution due to multiple unauthenticated and insufficiently authorized API endpoints

- Exploited (CISA KEV): no
- Published: 2026-07-30
- CVSS: 9.8 CRITICAL (v3.1)
- EPSS: 0.9% (61th percentile)
- CWE: CWE-78

IBM Langflow OSS 1.0.0 through 1.10.1  are vulnerable to unauthenticated remote code execution via environment variable injection in the MCP (Model Context Protocol) stdio launcher. The vulnerability exists in src/lfx/src/lfx/base/mcp/util.py where the DANGEROUS_ENV_VARS blocklist fails to include SHELLOPTS , BASHOPTS , and PS4 environment variables.

## 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 | 2026-09-16 | 48 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### F5

- 2026-09-16 · new · rule 200103690
  > Added: signature 200103690 "Langflow Remote Code Execution" (Command Execution, risk High), systems: Other Web Server. References: CVE-2026-12940.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

"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-2026-12940 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2026-12940