CVE-2026-77246 sooperset CVE debrief

Who should care

Defenders responsible for MCP Atlassian deployments should assess their exposure and prioritize upgrading to version 0.22.0. Those responsible for MCP Atlassian deployments should verify their configurations, assess their exposure, and prioritize upgrading to version 0.22.0. The impact of this vulnerability requires verification from official sources, and defenders should care about CVE-2026-77246 because it allows unauthorized file transfer in MCP Atlass

Why it matters

Defenders should care about CVE-2026-77246 because it allows unauthorized file transfer in MCP Atlassian deployments. Those responsible for MCP Atlassian deployments should assess their exposure, verify their configurations, and prioritize upgrading to version 0.22.0. The impact of this vulnerability requires verification from official sources.

• Potential unauthorized file transfer
• Possible exploitation of vulnerable deployments
• Verification of deployment configurations required
• Upgrade to version 0.22.0 recommended

Technical summary

MCP Atlassian, a Model Context Protocol (MCP) server for Atlassian products, is vulnerable to an authorization bypass. An attacker can send a server-local file to a selected attachment endpoint without proper authorization. The issue is fixed in version 0.22.0. This vulnerability arises from the server's acceptance of requests without proper authorization and its handling of attacker-controlled Atlassian service headers. Affected deployments should prioritize upgrading to version 0.22.0 and verify their configurations.

Defensive priority

Defenders should prioritize upgrading to version 0.22.0 and verify the configuration of their MCP Atlassian deployment.

Recommended defensive actions

• Upgrade to version 0.22.0
• Verify the configuration of your MCP Atlassian deployment
• 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 vulnerability allows an attacker to send a server-local file to a selected attachment endpoint without proper authorization. The issue is fixed in version 0.22.0. Evidence of this vulnerability includes the ability to invoke confluence_upload_attachment or the Jira attachment variant with a server-local file_path, causing the MCP process to send the file to the selected attachment endpoint. Defenders should verify their configurations, assess their exposure, and prioritize upgrading to version 0.22.0.

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.