CVE-2026-77268 sooperset CVE debrief

Who should care

System administrators and security teams responsible for local access control and token management in MCP Atlassian environments should review and update their practices to prevent unauthorized token reuse and ensure secure storage and handling of tokens. This includes verifying local access controls, reviewing token management practices, and updating to version 0.22.0 or later.

Why it matters

CVE-2026-77268 is a medium-severity vulnerability in MCP Atlassian that allows local users or processes to read access and refresh tokens and reuse the associated Atlassian session. System administrators and security teams should review local access controls and token management practices, and update to version 0.22.0 or later.

• Local access control review and remediation are required to prevent unauthorized token reuse.
• Token management practices should be verified to ensure secure storage and handling.
• Update to version 0.22.0 or later to fix the vulnerability.

Technical summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth fallback token directory and JSON file are created without explicit owner-only modes. Local users or processes with access through the resulting group or world permission bits can read access and refresh tokens and reuse the associated Atlassian session. The advisory provides details on the vulnerable input and processing flow through ~/.mcp-atlassian, oauth-<client_id>.json, access_token, and refresh_token.

Defensive priority

Medium priority for local access control review and token management

Recommended defensive actions

• Review local access controls and permissions for MCP Atlassian
• Verify token management and storage practices
• Update to version 0.22.0 or later
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• 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

Evidence notes

The advisory traces the vulnerable input and processing flow through ~/.mcp-atlassian, oauth-<client_id>.json, access_token, and refresh_token. Local users or processes with access through the resulting group or world permission bits can read access and refresh tokens and reuse the associated Atlassian session.

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.