CVE-2026-77249: mcp-atlassian Incomplete SSRF Fix in Jira User-Permission Lookup
Summary
CVE-2026-77249: Summary The fix for the SSRF vulnerability tracked as GHSA-7r34-79r5-rcc9 / CVE-2026-27826 is incomplete. Affects mcp-atlassian versions < 0.22.0. Fixed in 0.22.0. How to fix ↓
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Background
The mcp-atlassian package is a Python library designed to interact with Atlassian products like Jira and Confluence. It facilitates operations such as user management, issue tracking, and project management through REST APIs. This package is widely used in environments where Atlassian tools are integrated into workflows. However, it has been found to have a vulnerability related to Server-Side Request Forgery (SSRF), which could allow unauthorized access to internal resources.
Vulnerability Detail
The vulnerability arises from an incomplete fix for a previously identified SSRF issue (GHSA-7r34-79r5-rcc9). The method _lookup_user_by_permissions in the mcp-atlassian package uses the module-level requests.get instead of the session-based self.jira._session.get. This oversight allows an unauthenticated attacker to exploit the system by setting a public base URL that passes validation, leading to potential redirection of requests to internal addresses. The attacker can leverage this flaw to perform blind SSRF attacks, which may expose internal services and metadata endpoints.
How To Fix
Minimum fixed version
0.22.0
This is the first release that contains the fix.
pip install --upgrade "mcp-atlassian==0.22.0"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can modify the code in the affected method to use the session-based request instead of the module-level request. Replace the line: 'response = requests.get(url, params=params, auth=auth, headers=headers, verify=self.config.ssl_verify)' with 'response = self.jira._session.get(url, params=params, verify=self.config.ssl_verify)'. This change will ensure that the SSRF validation hook is applied.
Conclusion
The mcp-atlassian package has a vulnerability related to SSRF due to an incomplete fix in its user-permission lookup functionality. It is crucial to update to version 0.22.0 or later to mitigate the risk. Additionally, users can implement a temporary workaround by modifying the affected code. Regular monitoring for vulnerabilities using tools like Vulert can help maintain security.
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FAQ
Server-Side Request Forgery (SSRF) is a vulnerability that allows an attacker to send crafted requests from a vulnerable server to internal or external resources, potentially exposing sensitive data.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which allows you to monitor for open-source vulnerabilities without requiring signup.
The vulnerability can lead to unauthorized access to internal services, potential data exposure, and exploitation of internal APIs, which may compromise the security of the entire system.
Yes, the patch is available in version 0.22.0 of the mcp-atlassian package. It is recommended to update to this version to mitigate the vulnerability.
The CVSS score for this vulnerability is 5.3, indicating a moderate severity level.
References
Related vulnerabilities
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