CVE-2026-77250

medium

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira).

Vendor / product: Mcp-atlassian — mcp atlassian

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-.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.

CVSS

6.1

6.1 (CVSS v3.1)

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

Severity source: NVD CVSS v3.1 (security-advisories@github.com)

Timeline (UTC)

Published: 2026-09-22 18:17

Modified: 2026-09-29 14:22

NVD status: Analyzed

Last synced 3 days ago

Verified against the source API 2026-10-27 06:55 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mcp-atlassian / mcp_atlassian <0.22.0

Weakness classification (CWE)

CWE-312

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6

Patch / mitigation: https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460

Patch / mitigation: https://github.com/sooperset/mcp-atlassian/pull/1448

References

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/pull/1448 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:55 UTC · record ↗

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CVE-2026-77250

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