CVE-2026-12940 IBM CVE debrief

Who should care

Defenders responsible for systems using IBM Langflow OSS versions 1.0.0 through 1.10.1 should assess exposure and apply remediation or compensating controls. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify exposure and apply remediation to prevent unauthenticated remote code execution.

Why it matters

Defenders should prioritize verifying exposure and applying remediation for IBM Langflow OSS versions 1.0.0 through 1.10.1 due to the risk of unauthenticated remote code execution via environment variable injection.

• Potential for unauthenticated remote code execution
• Need for verification of exposure and application of remediation
• Possible impact on systems using IBM Langflow OSS versions 1.0.0 through 1.10.1

Technical summary

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, allowing for unauthenticated remote code execution via environment variable injection in the MCP stdio launcher. This oversight enables attackers to inject malicious environment variables, potentially leading to arbitrary code execution. The vulnerability is confirmed in IBM Langflow OSS versions 1.0.0 through 1.10.1, and defenders should prioritize verifying exposure and applying remediation.

Defensive priority

Defenders should prioritize verifying exposure and applying remediation, focusing on systems using IBM Langflow OSS versions 1.0.0 through 1.10.1.

Recommended defensive actions

• Verify inventory of systems using IBM Langflow OSS versions 1.0.0 through 1.10.1
• Apply remediation or compensating controls as recommended by the vendor
• Monitor for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The vulnerability is confirmed in IBM Langflow OSS versions 1.0.0 through 1.10.1. Official sources indicate unauthenticated remote code execution via environment variable injection. The DANGEROUS_ENV_VARS blocklist fails to include SHELLOPTS, BASHOPTS, and PS4 environment variables, allowing for potential code execution. Defenders should verify exposure and apply remediation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.