Vulnerability in Mcp-Atlassian Mcp Atlassian
CVE-2026-77268
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth fallback token directory and JSON file are created without explicit owner-only modes. Local users or processes with access through the resulting group or world permission bits can read access and refresh tokens and reuse the associated Atlassian session. The advisory traces the vulnerable input and processing flow through ~/.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 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (4.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 4.4% 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: 0.002 · 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-4596-2p6p-28cv (Exploit, Mitigation, 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-2026-77268?
- CVE-2026-77268 is a medium-severity vulnerability in Mcp-Atlassian Mcp Atlassian, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 5.5/10. Published 2026-09-22.
- How severe is CVE-2026-77268?
- Medium severity. CVSS v3 base score is 5.5 out of 10.