CVE-2026-77242 sooperset CVE debrief

Who should care

Defenders of MCP Atlassian instances, especially those with internal or metadata endpoints, should assess exposure and prioritize upgrading to version 0.22.0 or later. Defenders should prioritize verifying exposure of MCP Atlassian instances, especially those with internal or metadata endpoints, and upgrade to version 0.22.0 or later. Operators of affected MCP Atlassian instances should verify exposure, prioritize upgrading to version 0.22.0 or later, and

Why it matters

The CVE-2026-77242 vulnerability in MCP Atlassian allows for SSRF attacks, potentially leading to unauthorized access to internal or metadata endpoints. Defenders should prioritize verifying exposure and upgrading to version 0.22.0 or later.

• Potential unauthorized access to internal or metadata endpoints
• Possible bypass of earlier CVE-2026-27826 remediation
• Need for verification of MCP Atlassian instance exposure
• Priority for upgrading to version 0.22.0 or later

Technical summary

The validate_url_for_ssrf function in MCP Atlassian does not properly validate hostnames, allowing for SSRF attacks. This issue arises from the function's validation of a hostname's resolved addresses, which can be bypassed using a short-lived DNS answer that is public during validation and private during connection. The vulnerability was fixed in version 0.22.0. A vulnerability in MCP Atlassian, a Model Context Protocol (MCP) server for Atlassian products, allows unauthenticated access to internal or metadata endpoints. The issue arises from the validate_url_for_ssrf function's validation of a hostname's resolved addresses, which can be bypassed using a short-lived DNS answer that is public during validation

Defensive priority

Defenders should prioritize verifying exposure of MCP Atlassian instances, especially those with internal or metadata endpoints, and upgrade to version 0.22.0 or later.

Recommended defensive actions

• Verify exposure of MCP Atlassian instances
• Upgrade to version 0.22.0 or later
• Monitor internal or metadata endpoints for unauthorized access
• 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 vulnerability is caused by the validate_url_for_ssrf function not properly validating hostnames, allowing for SSRF attacks. The issue was fixed in version 0.22.0. The validate_url_for_ssrf function in MCP Atlassian does not properly validate hostnames, allowing for SSRF attacks. This issue arises from the function's validation of a hostname's resolved addresses, which can be bypassed using a short-lived DNS answer that is public during validation and private during connection. Defenders should verify exposure of MCP Atlassian, fix

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.