CVE-2026-77271: mcp-atlassian Incomplete Path Traversal Fix Leading to RCE
Summary
CVE-2026-77271: The path traversal fix introduced in v0.17.0 (GHSA-xjgw-4wvw-rgm4) is incomplete. Affects mcp-atlassian versions < 0.22.0. Fixed in 0.22.0. How to fix ↓
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Background
mcp-atlassian is a Python package designed for interacting with Atlassian products, such as Confluence. It provides utilities for managing attachments and other resources within these applications. The package is widely used in environments where automation and integration with Atlassian tools are required. However, it has been found to have a critical vulnerability that allows for remote code execution due to an incomplete fix for path traversal issues.
Vulnerability Detail
The vulnerability arises from the incomplete path traversal fix implemented in version 0.17.0 of the mcp-atlassian package. The function validate_safe_path() defaults to the current working directory (CWD) when no base directory is specified, allowing attackers to overwrite Python source modules within the application directory. This oversight can lead to remote code execution (RCE) when the application is restarted, as the malicious payload can be executed. The vulnerability affects versions 0.17.0 through 0.21.0, with a CVSS score of 8.3, indicating a high severity.
How To Fix
Latest published version: 0.23.1 as of 23 Oct 2026
pip install --upgrade "mcp-atlassian==0.23.1"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
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 where validate_safe_path() is called to include a specific base directory instead of relying on the current working directory. For example:
_DOWNLOAD_BASE = Path(
os.environ.get("MCP_DOWNLOAD_DIR", "/tmp/mcp-downloads")
).resolve()
validate_safe_path(target_path, base_dir=_DOWNLOAD_BASE)
Conclusion
The mcp-atlassian package has a critical vulnerability (CVE-2026-77271) that allows for remote code execution due to an incomplete path traversal fix. Users are advised to update to version 0.22.0 or later to secure their applications. For immediate mitigation, a workaround is available to specify a base directory in the code.
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FAQ
CVE-2026-77271 is a vulnerability in the mcp-atlassian package that allows for remote code execution due to an incomplete path traversal fix.
Versions 0.17.0 through 0.21.0 of the mcp-atlassian package are affected by this vulnerability.
You can use Vulert to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without requiring signup.
The CVSS score of this vulnerability is 8.3, indicating a high severity level.
If you cannot update the package immediately, implement the provided workaround to specify a base directory for the validate_safe_path() function to mitigate the risk.
References
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