CVE-2026-77256: CWE-732: Incorrect Permission Assignment for Critical Resource in sooperset mcp-atlassian
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the plaintext OAuth fallback file containing refresh and access tokens is written with permissions inherited from the process umask. Under common or permissive configurations, other local users can read the backup and retain Atlassian access through the refresh token. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens_to_file, refresh_token, access_token, and umask, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
AI Analysis
Technical Summary
MCP Atlassian versions before 0.22.0 write a plaintext OAuth fallback file containing refresh and access tokens with permissions inherited from the process umask. Under common or permissive umask settings, this results in incorrect permission assignment (CWE-732), allowing other local users to read the file and retain Atlassian access via the refresh token. The vulnerability affects the OAuthConfig._save_tokens_to_file function and related token handling code paths. The flaw is resolved in version 0.22.0.
Potential Impact
An attacker with local access to the system can read the plaintext OAuth fallback file containing refresh and access tokens due to overly permissive file permissions. This enables unauthorized retention of Atlassian access, potentially compromising Confluence and Jira resources. The vulnerability does not require user interaction and has a high impact on confidentiality.
Mitigation Recommendations
Upgrade MCP Atlassian to version 0.22.0 or later, where the issue is fixed. This update ensures the OAuth fallback file is created with secure permissions, preventing unauthorized local access to sensitive tokens.
CVE-2026-77256: CWE-732: Incorrect Permission Assignment for Critical Resource in sooperset mcp-atlassian
Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the plaintext OAuth fallback file containing refresh and access tokens is written with permissions inherited from the process umask. Under common or permissive configurations, other local users can read the backup and retain Atlassian access through the refresh token. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens_to_file, refresh_token, access_token, and umask, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
CVSS v4.0
Score 8.3high
Affected software
sooperset
mcp-atlassian
pkg:github/sooperset/mcp-atlassianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
MCP Atlassian versions before 0.22.0 write a plaintext OAuth fallback file containing refresh and access tokens with permissions inherited from the process umask. Under common or permissive umask settings, this results in incorrect permission assignment (CWE-732), allowing other local users to read the file and retain Atlassian access via the refresh token. The vulnerability affects the OAuthConfig._save_tokens_to_file function and related token handling code paths. The flaw is resolved in version 0.22.0.
Potential Impact
An attacker with local access to the system can read the plaintext OAuth fallback file containing refresh and access tokens due to overly permissive file permissions. This enables unauthorized retention of Atlassian access, potentially compromising Confluence and Jira resources. The vulnerability does not require user interaction and has a high impact on confidentiality.
Mitigation Recommendations
Upgrade MCP Atlassian to version 0.22.0 or later, where the issue is fixed. This update ensures the OAuth fallback file is created with secure permissions, preventing unauthorized local access to sensitive tokens.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T19:02:23.417Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ab2d108f7a7c541069ead04
Added to database: 09/22/2026, 19:03:36 UTC
Last enriched: 09/22/2026, 19:17:51 UTC
Last updated: 09/22/2026, 19:33:28 UTC
Views: 3
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