CVE-2026-49856 vmoranv CVE debrief

Who should care

Defenders responsible for securing internal networks and MCP servers should assess exposure and take action to prevent exploitation. This includes reviewing the vulnerability details, verifying the exposure of internal networks to the @jshookmcp/jshook MCP server, and updating to version 0.3.2 or later. Additionally, defenders should monitor for suspicious activity and review compensating controls for exposed systems.

Why it matters

Defenders should prioritize verifying exposure of internal networks and updating to version 0.3.2 to prevent potential SSRF bypass and internal network reconnaissance.

• Potential exposure of internal network reachability and route mapping
• Bypass of SSRF protections for ICMP probe and traceroute tools
• Increased risk of internal network reconnaissance

Technical summary

The @jshookmcp/jshook MCP server has a vulnerability that allows an MCP client to bypass SSRF protections and probe internal addresses. The issue arises from the ICMP probe and traceroute tools resolving the target and invoking the native ICMP/traceroute sink directly, rather than being subject to the central SSRF authorization policy. This exposes an internal reachability and route mapping primitive from the server network position.

Defensive priority

Defenders should prioritize verifying exposure of internal networks and updating to version 0.3.2.

Recommended defensive actions

• Verify exposure of internal networks to the @jshookmcp/jshook MCP server
• Update to version 0.3.2 or later
• Monitor for suspicious activity
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and its fix. However, additional information on affected systems and exploitation is limited. Defenders should verify the exposure of internal networks to the @jshookmcp/jshook MCP server and review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. The CVE record was published on 2026-08-13T15:19:41.563Z and has not been modified since then.

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.