CVE-2026-77250: MCP Atlassian — MEDIUM

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...

Full CISO analysis pending enrichment.

What systems are affected?

Package	Ecosystem	Vulnerable Range	Patched
MCP Atlassian	pip	—	No patch
1 dependents 33% patched ~10d to patch Full package profile →

Do you use MCP Atlassian? You're affected.

How severe is it?

CVSS 3.1

6.1 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

N/A

What is the attack surface?

AV Local

AC Low

PR Low

UI None

S Unchanged

C High

I Low

A None

What should I do?

No patch available

Monitor for updates. Consider compensating controls or temporary mitigations.

Which compliance frameworks are affected?

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is 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.

Is CVE-2026-77250 actively exploited?

No confirmed active exploitation of CVE-2026-77250 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-77250?

No patch is currently available. Monitor vendor advisories for updates.

What is the CVSS score for CVE-2026-77250?

CVE-2026-77250 has a CVSS v3.1 base score of 6.1 (MEDIUM).

What are the technical details?

Original Advisory

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.

Weaknesses (CWE)

CWE-312 Cleartext Storage of Sensitive Information

CWE-312 — Cleartext Storage of Sensitive Information: The product stores sensitive information in cleartext within a resource that might be accessible to another control sphere.

[Implementation, System Configuration, Operation] When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to encrypt the data at rest. [REF-1297] [REF-1299] [REF-1301]
[Implementation, System Configuration, Operation] In some systems/environments such as cloud, the use of "double encryption" (at both the software and hardware layer) might be required, and the developer might be solely responsible for both layers, instead of shared responsibility with the administrator of the broader system/environment.

Source: MITRE CWE corpus.