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TI-2026-53934 Aliases CVE-2026-77250GHSA-g5xv-mhgm-v5f6

MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions

Priority MEDIUM 60CWE-312Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-312.

Summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, OAuthConfig writes a plaintext fallback file containing access and refresh tokens under the user's .mcp-atlassian directory using process-default permissions. On systems with a permissive umask, same-group or other local users and processes can read the persisted tokens and reuse the associated Atlassian access. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens, ~/.mcp-atlassian/oauth-<client_id>.json, access_token, and refresh_token, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00115 1st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mcp-atlassian (sooperset): 0.22.0mcp-atlassian (PyPI): 0.22.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
soopersetmcp-atlassianbefore 0.22.00.22.0Patch availableCNA
—mcp-atlassian (PyPI)before 0.22.00.22.0Patch availableGHSA-g5xv-mhgm-v5f6
  • mcp-atlassian Vendorsooperset Affected before 0.22.0 Fixed in 0.22.0 Patch available CNA
  • mcp-atlassian (PyPI) Vendor— Affected before 0.22.0 Fixed in 0.22.0 Patch available GHSA-g5xv-mhgm-v5f6

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*before 0.22.0VulnerableMcp-atlassian
  • cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* Versions before 0.22.0 Vulnerable ·Mcp-atlassian

Remediation

  • Fix · CNA mcp-atlassian (sooperset) Fixed in 0.22.0
  • Fix · GHSA-g5xv-mhgm-v5f6 mcp-atlassian (PyPI) Fixed in 0.22.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-77250
  2. 2026-10-03 Alias added: GHSA-g5xv-mhgm-v5f6

References

Exploit 1

Patch 2

Advisory 1

Other 2

  • TI-2026-53938 MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials CVSS 3.1CRITICAL 9.1
  • TI-2026-53957 MCP Atlassian: SSRF Protection Bypass CVSS 4.0HIGH 8.8
  • TI-2026-53935 Protection mechanism failure in sooperset mcp-atlassian CVSS 4.0HIGH 8.3
  • TI-2026-53946 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
  • TI-2026-53932 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
  • TI-2026-22177 Path traversal in sooperset mcp-atlassian CVSS 3.1CRITICAL 9.1
See all 33 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences