Vulnerability in Mcp-Atlassian Mcp Atlassian
CVE-2026-77250
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.001 (1.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: +0.000
Affected products
- Mcp-Atlassian Mcp Atlassian
- Sooperset Mcp-Atlassian — versions < 0.22.0
Weakness classification (CWE)
References
- github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6 (Exploit, Vendor Advisory)
- github.com/sooperset/mcp-atlassian/pull/1448 (Patch, Issue Tracking)
- github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e… (Patch)
- github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-77250?
- CVE-2026-77250 is a medium-severity vulnerability in Mcp-Atlassian Mcp Atlassian, classified under Cleartext Storage of Sensitive Information. CVSS score: 6.1/10. Published 2026-09-22.
- How severe is CVE-2026-77250?
- Medium severity. CVSS v3 base score is 6.1 out of 10.