# CVE-2026-77267: mcp-atlassian incomplete SSRF remediation in URL header processing

Source: https://junglewise.ai/threats/cve-2026-77267-mcp-atlassian-incomplete-ssrf-remediation-in-url-header  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-22. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-77267 · Severity: high · CVSS 4 · Published 2026-09-22

mcp-atlassian is a PyPI package that integrates with Atlassian services (Jira and Confluence). The package fails to properly validate URLs provided via HTTP headers before making authenticated server-to-server requests, allowing an attacker to redirect those requests to internal services—such as AWS metadata endpoints or other private systems—potentially exposing sensitive configuration data or enabling lateral movement within a network.

Technologies: [mcp-atlassian (PyPI)](https://junglewise.ai/threats/technologies/mcp-atlassian). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-77267 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77267 being exploited in the wild.

**How severe is CVE-2026-77267?** High severity, with a CVSS score of 4, published 22 September 2026.

**Which products and versions are affected?** mcp-atlassian (PyPI) < 0.22.0, ECOSYSTEM:introduced=0,fixed=0.22.0.

**Is there a fix for CVE-2026-77267?** Yes. mcp-atlassian (PyPI): upgrade to 0.22.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-77267 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-77267?** Check whether you run mcp-atlassian (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- mcp-atlassian (PyPI): upgrade to 0.22.0 or later

  ```sh
  pip install "mcp-atlassian>=0.22.0"
  ```


## Technical details

The vulnerability is an incomplete Server-Side Request Forgery (SSRF) remediation in the UserTokenMiddleware component. The `_process_authentication_headers()` function in main.py extracts URLs from the `X-Atlassian-Jira-Url` and `X-Atlassian-Confluence-Url` HTTP headers and passes them directly to JiraConfig/ConfluenceConfig constructors without any SSRF validation (no IP range checks, no hostname allowlist, no loopback/link-local filtering). The fetcher then makes authenticated HTTP requests to these attacker-controlled URLs. The attack vector is network-based and does not require authentication; an attacker sends a crafted HTTP request with a malicious header value. A prior fix attempted to add URL validation to some code paths but did not cover the header-extraction pathway. Attackers can exploit this to access AWS instance metadata (e.g., http://169.254.169.254/latest/meta-data/) or internal services, potentially exfiltrating credentials or configuration data.

## Affected products

- mcp-atlassian mcp-atlassian all versions before commit 5cd697dfce91

## Identifiers

- CVE-2026-77267
- GHSA-5wf4-jqxh-8gm3
- PYSEC-2026-4084

## Timeline

- 2026-09-22: disclosed
- advisory: GHSA-5wf4-jqxh-8gm3

## Related threats

- [Atlassian MCP reflected XSS in OAuth setup callback handler](https://junglewise.ai/threats/cve-2026-77272-atlassian-mcp-reflected-xss-in-oauth-setup-callback-handler)
- [Atlassian MCP path traversal in upload_attachment allows arbitrary file read](https://junglewise.ai/threats/cve-2026-77269-atlassian-mcp-path-traversal-in-upload-attachment-allows)
- [Atlassian MCP insecure OAuth token file permissions](https://junglewise.ai/threats/cve-2026-77268-atlassian-mcp-insecure-oauth-token-file-permissions)
- [MCP Atlassian path traversal in upload_attachment](https://junglewise.ai/threats/cve-2026-77266-mcp-atlassian-path-traversal-in-upload-attachment)
- [sooperset mcp-atlassian path traversal in confluence_upload_attachment](https://junglewise.ai/threats/cve-2026-77262-sooperset-mcp-atlassian-path-traversal-in-confluence-upload)