Summary
MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read (incomplete fix for CVE-2026-27825)
The confluence_upload_attachment and confluence_upload_attachments MCP tools accept a file_path parameter and do not validate that the path is confined to an allowed directory before opening the file. An attacker who can call these tools can read any file accessible to the MCP server process (SSH keys, .env files, API credentials) and exfiltrate it by uploading it to Confluence.
Note: The Jira upload_attachment mixin method in jira/attachments.py has the same missing validation, but it is NOT registered as an MCP tool in servers/jira.py and is therefore not currently reachable via MCP. It should still be patched to prevent future exposure if Jira upload tools are added.
This is an incomplete fix for CVE-2026-27825. That CVE was patched by adding validate_safe_path() to download operations (v0.17.0). The same protection was not applied to upload operations.
Details
validate_safe_path() is imported in both confluence/attachments.py and jira/attachments.py and is correctly called in all download functions. It is absent from the Confluence upload functions (which are exposed as MCP tools) and from the Jira upload mixin methods (which are not currently registered as MCP tools but should still be patched).
Download (protected, correctly patched):
# confluence/attachments.py:222-223
validate_safe_path(target_path) # resolves symlinks + checks is_relative_to(cwd)
Upload (vulnerable, not patched):
# confluence/attachments.py:64-79, NO validate_safe_path() call
if not os.path.isabs(file_path):
file_path = os.path.abspath(file_path) # normalizes but does NOT restrict
# ...
files = {"file": (filename, open(file_path, "rb"))} # opens arbitrary file
Same pattern in jira/attachments.py:386.
Proof of Concept
# Call via MCP client
await session.call_tool("confluence_upload_attachment", {
"content_id": "12345",
"file_path": "/home/user/.ssh/id_rsa" # absolute path, no traversal needed
})
# SSH private key is now a Confluence attachment
# Retrieve via: confluence_download_attachment or Confluence UI
Impact
Arbitrary file read from the server filesystem. High-value targets: SSH private keys, .env files, AWS/GCP credentials, database configuration, source code.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-77269 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.22.0); upgrading removes the vulnerable code path.
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.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Add validate_safe_path(file_path) call in confluence/attachments.py:upload_attachment() (reachable via MCP) and jira/attachments.py:upload_attachment() (not currently reachable via MCP, but should be patched preventively), consistent with the existing download protection. No changes to validate_safe_path() itself are needed.
# Add after os.path.abspath() call:
try:
validate_safe_path(file_path)
except ValueError as e:
return {"success": False, "error": str(e)}
Frequently Asked Questions
- What is CVE-2026-77269? CVE-2026-77269 is a medium-severity path traversal vulnerability in mcp-atlassian (pip), affecting versions < 0.22.0. It is fixed in 0.22.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2026-77269? CVE-2026-77269 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of mcp-atlassian are affected by CVE-2026-77269? mcp-atlassian (pip) versions < 0.22.0 is affected.
- Is there a fix for CVE-2026-77269? Yes. CVE-2026-77269 is fixed in 0.22.0. Upgrade to this version or later.
- Is CVE-2026-77269 exploitable, and should I be worried? Whether CVE-2026-77269 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-2026-77269 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-2026-77269? Upgrade
mcp-atlassianto 0.22.0 or later.