CVE-2026-77256

MediumCVSS 6.5/10Last modified Sep 28, 2026

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.

Metrics

CVSS 3.1 6.5/10CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Weakness enumeration

CWE-732

Affected software

No affected versions have been published.

Timeline

Published
Sep 22, 2026
Last modified
Sep 28, 2026
NVD status
Analyzed

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CVE-2026-77256: Medium severity, CVSS 6.5 | Vulnix