CVE-2026-77270 sooperset CVE debrief

Who should care

MCP Atlassian server administrators and users with upload access should assess exposure, prioritize remediation, and monitor for suspicious activity related to file access and uploads. This includes reviewing compensating controls for exposed systems, verifying affected scope, and tracking exceptions and retesting remediated assets.

Why it matters

CVE-2026-77270 is a medium-severity vulnerability in MCP Atlassian server that allows file disclosure. Defenders should assess exposure, prioritize remediation, and monitor for suspicious activity.

• File disclosure may lead to sensitive information exposure
• Requires verification of affected versions and remediation status
• May require monitoring and logging enhancements

Technical summary

The MCP Atlassian server vulnerability allows an attacker to disclose any file readable by the server process by exploiting the Jira and Confluence attachment upload tools. This occurs because the tools treat caller-controlled file_path values as trusted server-local paths. The issue is fixed in version 0.22.0. Defenders should assess exposure, prioritize remediation, and monitor for suspicious activity related to file access and uploads. The vulnerability has a medium severity and requires verification of affected versions and remediation status.

Defensive priority

Medium priority for MCP Atlassian server administrators

Recommended defensive actions

• Update MCP Atlassian server to version 0.22.0 or later
• Restrict access to the MCP Atlassian server
• Monitor server logs 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 advisory describes a file disclosure vulnerability in MCP Atlassian server versions prior to 0.22.0, where the Jira and Confluence attachment upload tools treat caller-controlled file_path values as trusted server-local paths. This allows an MCP caller with upload access to disclose any file readable by the server process. The issue is fixed in version 0.22.0. Defenders should verify affected scope, assess exposure, and prioritize 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.