What is CVE-2026-77250?

CVE-2026-77250 is a medium-severity vulnerability in Sooperset 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.

Vulnerability in Sooperset 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 2026-09-22 · last modified 2026-09-22.

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

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Sooperset Mcp-Atlassian — versions < 0.22.0

Weakness classification (CWE)

CWE-312 — Cleartext Storage of Sensitive Information

References

Frequently asked questions

What is CVE-2026-77250?: CVE-2026-77250 is a medium-severity vulnerability in Sooperset 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.