CVE-2026-77267: mcp-atlassian Incomplete SSRF Remediation Vulnerability
Summary
CVE-2026-77267: mcp-atlassian has an incomplete SSRF remediation. 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 to facilitate interactions with Atlassian products such as Jira and Confluence. It provides a set of APIs that allow developers to automate tasks and integrate these services into their applications. However, the package has a vulnerability related to Server-Side Request Forgery (SSRF), which can lead to unauthorized access to internal services.
Vulnerability Detail
The vulnerability arises from the UserTokenMiddleware, which extracts URLs from the HTTP headers X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url without proper validation. This means that an attacker can manipulate these headers to direct the application to make requests to arbitrary URLs, including internal services or sensitive endpoints like AWS instance metadata. The lack of validation allows for potential exploitation, leading to unauthorized data access and security breaches.
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 implement your own validation for the URLs extracted from the headers before they are passed to the API client constructors. This can be done by checking the URLs against an allowlist of permitted hostnames or rejecting private/loopback/link-local IP ranges. Here is a sample code snippet for URL validation:
import re
def validate_url(url):
# Example allowlist
allowlist = ["https://your-allowed-domain.com"]
if any(re.match(pattern, url) for pattern in allowlist):
return True
return False
# Usage
if validate_url(jira_url_str):
service_headers["X-Atlassian-Jira-Url"] = jira_url_str
else:
raise ValueError("Invalid URL")
Conclusion
The mcp-atlassian package has a significant SSRF vulnerability that can be exploited by attackers to access unauthorized resources. It is crucial to update to the patched version to secure your application. Implementing URL validation can serve as a temporary measure until the update is applied.
See every vulnerability recorded for mcp-atlassian →
FAQ
Server-Side Request Forgery (SSRF) is a security vulnerability that allows an attacker to send crafted requests from a vulnerable server to internal or external resources.
An attacker can exploit this vulnerability to access internal services or sensitive data, potentially leading to data breaches or unauthorized actions within your network.
Yes, the vulnerability has been patched in versions of mcp-atlassian greater than or equal to commit 5cd697dfce91.
Implement URL validation as a temporary workaround to mitigate the risk until you can update to the patched version.
You can use Vulert, which monitors and alerts in real-time for open-source vulnerabilities in your software without requiring access to the code or installation.
References
Related vulnerabilities
Recent vulnerabilities recorded for mcp-atlassian.
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