Summary
mcp-atlassian has an incomplete SSRF remediation
The UserTokenMiddleware extracts URLs from X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url HTTP headers and passes them directly to API client constructors without any SSRF validation.
Affected Package
- Ecosystem: PyPI
- Package: mcp-atlassian
- Affected versions: all versions before fix commit 5cd697dfce91
- Patched versions: >= commit 5cd697dfce91
Details
In main.py, _process_authentication_headers() extracts URLs from ASGI headers without validation. In dependencies.py, get_jira_fetcher() creates JiraConfig with url=jira_url_header directly. There is no validate_url call, no IP range check, no hostname validation.
The fix adds URL validation to some paths but the header-based URL extraction in _process_authentication_headers() still passes raw URLs through. The derived config objects use the header URL directly and the fetcher makes HTTP requests to that URL.
PoC
jira_url_header = headers.get(b"x-atlassian-jira-url")
jira_url_str = jira_url_header.decode("latin-1") if jira_url_header else None
service_headers["X-Atlassian-Jira-Url"] = jira_url_str
Steps to reproduce:
git clone https://github.com/sooperset/mcp-atlassian /tmp/mcp-atlassian_testcd /tmp/mcp-atlassian_test && git checkout 5cd697dfce91~1pip install -e .python3 poc.py
Expected output:
VULNERABILITY CONFIRMED
User-supplied URLs from HTTP headers passed directly to JiraConfig/JiraFetcher with no SSRF validation
Suggested Remediation
Validate all user-supplied URLs against an allowlist of permitted hostnames or reject private/loopback/link-local IP ranges. Consider requiring server-side configuration of allowed Atlassian instance URLs.
Impact
An attacker can set X-Atlassian-Jira-Url: http://169.254.169.254/latest/meta-data/ to access AWS instance metadata, or target any internal service. The server makes authenticated HTTP requests to the attacker-specified URL.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is CVE-2026-77267? CVE-2026-77267 is a high-severity server-side request forgery (SSRF) vulnerability in mcp-atlassian (pip), affecting versions < 0.22.0. It is fixed in 0.22.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- Which versions of mcp-atlassian are affected by CVE-2026-77267? mcp-atlassian (pip) versions < 0.22.0 is affected.
- Is there a fix for CVE-2026-77267? Yes. CVE-2026-77267 is fixed in 0.22.0. Upgrade to this version or later.
- Is CVE-2026-77267 exploitable, and should I be worried? Whether CVE-2026-77267 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-77267 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-77267? Upgrade
mcp-atlassianto 0.22.0 or later.