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CVE-2026-11918 IBM CVE debrief

IBM ContextForge MCP Gateway vulnerability allows authenticated users to bypass protection mechanisms due to incomplete recursive inspection of nested payload content. This medium-severity vulnerability has a CVSS score of 5.4 and affects IBM ContextForge MCP Gateway deployments. Defenders should assess exposure, verify remediation efforts, and update incident response plans as needed. The vulnerability is caused by incomplete recursive inspection of nested payload content, which allows authenticated users to bypass protection mechanisms. IBM has released an update to address the vulnerability, and defenders should verify if an update is available to address the vulnerability.

Vendor
IBM
Product
ContextForge MCP Gateway
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-15
Original CVE updated
2026-09-20
Advisory published
2026-09-15
Advisory updated
2026-09-20

Who should care

Defenders responsible for IBM ContextForge MCP Gateway deployments should assess exposure and verify if an update is available to address the vulnerability.

Why it matters

CVE-2026-11918 is a medium-severity vulnerability in IBM ContextForge MCP Gateway that allows authenticated users to bypass protection mechanisms. Defenders should assess exposure, verify remediation efforts, and update incident response plans as needed.

  • Defenders need to verify if IBM ContextForge MCP Gateway is used in their environment and assess the risk of authenticated users bypassing protection mechanisms.
  • Incident response teams should review and update plans to account for potential bypass of protection mechanisms.
  • Security teams should prioritize verification of IBM's remediation efforts and ensure that compensating controls are in place if necessary.

Technical summary

The IBM ContextForge MCP Gateway vulnerability (CVE-2026-11918) allows an authenticated user to bypass protection mechanisms due to incomplete recursive inspection of nested payload content. This medium-severity vulnerability has a CVSS score of 5.4.

Defensive priority

Medium priority for defenders to assess and verify vulnerability in IBM ContextForge MCP Gateway.

Recommended defensive actions

  • Assess exposure of IBM ContextForge MCP Gateway in your environment
  • Verify if IBM has released an update to address the vulnerability
  • Review and update incident response plans to account for potential bypass of protection mechanisms

Evidence notes

Evidence from IBM and NVD indicates a medium-severity vulnerability in IBM ContextForge MCP Gateway, but details are limited. The CVE record was published on 2026-09-15T18:17:12.677Z and has not been modified since then. IBM support page with additional information on the vulnerability (ref-3) provides further context. Defenders should verify if IBM ContextForge MCP Gateway is used in their environment and assess the risk of authenticated users bypassing protection mechanisms. The NVD

Sources and references

Verified primary and authoritative sources

  • CVE-2026-11918 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-11918

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-11918 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-11918

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental 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.