sooperset MCP Atlassian up to 0.21.x OAuthConfig oauth-.json OAuthConfig._save_tokens access_token/refresh_token permission

Summaryinfo

A vulnerability classified as problematic has been found in sooperset MCP Atlassian up to 0.21.x. Impacted is the function OAuthConfig._save_tokens of the file .mcp-atlassian/oauth-.json of the component OAuthConfig. This manipulation of the argument access_token/refresh_token causes permission. The identification of this vulnerability is CVE-2026-77250. The attack can only be executed locally. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in sooperset MCP Atlassian up to 0.21.x. It has been declared as problematic. Affected by this vulnerability is the function OAuthConfig._save_tokens of the file .mcp-atlassian/oauth-.json of the component OAuthConfig. The manipulation of the argument access_token/refresh_token with an unknown input leads to a permission vulnerability. The CWE definition for the vulnerability is CWE-275. As an impact it is known to affect confidentiality. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-77250 since 08/20/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1222 for this issue.

By approaching the search of inurl:.mcp-atlassian/oauth-.json it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 0.22.0 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Artificial Intelligence Software

Vendor

• sooperset

Name

• MCP Atlassian

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

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