CVE-2026-77268
MCP Atlassian: Insecure File Permissions on OAuth Token Storage
Description
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.
INFO
Published Date :
Sept. 22, 2026, 7:16 p.m.
Last Modified :
Sept. 29, 2026, 6:59 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-77268
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update MCP Atlassian to version 0.22.0.
- Verify file permissions for token directories.
- Remove sensitive tokens if compromised.
- Restrict access to token storage.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-77268.
| URL | Resource |
|---|---|
| https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 | Patch |
| https://github.com/sooperset/mcp-atlassian/pull/1448 | Issue Tracking Patch |
| https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 | Release Notes |
| https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-4596-2p6p-28cv | Exploit Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-77268 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-77268
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-77268 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-77268 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 29, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* versions up to (excluding) 0.22.0 Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/pull/1448 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-4596-2p6p-28cv Types: Exploit, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 23, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-77268', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-23T14:10:18.373472Z'} -
New CVE Received by [email protected]
Sep. 22, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-732 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/77xxx/CVE-2026-77268.json">CVE-2026-77268</a> Added Reference https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 Added Reference https://github.com/sooperset/mcp-atlassian/pull/1448 Added Reference https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 Added Reference https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-4596-2p6p-28cv