CVE-2026-77267

mcp-atlassian has an incomplete SSRF remediation

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Published Sep 22, 2026 CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed
Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers are processed by _process_authentication_headers and used to construct Atlassian fetchers without calling validate_url_for_ssrf. A caller who can set these headers can supply an internal or metadata-service URL and cause the server to send requests to that destination, bypassing the incomplete CVE-2026-27826 remediation. This issue is fixed in version 0.22.0.

Analysis

AI-generated

Technical impact

The MCP Atlassian server builds Atlassian fetchers from the X‑Atlassian‑Jira‑Url and X‑Atlassian‑Confluence‑Url headers without calling the URL‑validation routine, allowing a remote caller to supply internal or metadata‑service URLs and force the server to issue requests to those destinations. This bypasses the incomplete remediation of CVE‑2026‑27826 and can expose internal network resources or sensitive metadata to an attacker, potentially enabling data exfiltration or internal system compromise.

Affected Systems

sooperset’ MCP Atlassian server, versions earlier than 0.22.0

Risk and Exploitability

The CVSS score of 8.3 indicates high severity. Based on the description, the likely attack vector is remote over the network, and an attacker who can set custom HTTP headers can exploit this flaw with no special prerequisites. EPSS is not available, and the vulnerability is not listed in the CISA KEV catalog, so the assigned score reflects the inherent risk rather than known exploitation activity.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade MCP Atlassian to version 0.22.0 or later to include the missing validate_url_for_ssrf check
  • If an upgrade is not currently possible, enforce strict validation or a whitelist for the X‑Atlassian‑Jira‑Url and X‑Atlassian‑Confluence‑Url headers to restrict URLs to approved hosts
  • As a temporary workaround, remove or disable the ability to set these headers in incoming requests, or route traffic through a proxy that blocks internal or metadata‑service URLs

Generated by OpenCVE AI on September 22, 2026 at 20:12 UTC.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-5wf4-jqxh-8gm3 mcp-atlassian has an incomplete SSRF remediation
History
Type Values Removed Values Added
First Time appeared Mcp-atlassian
Mcp-atlassian mcp Atlassian
CPEs cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*
Vendors & Products Mcp-atlassian
Mcp-atlassian mcp Atlassian
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'}
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
First Time appeared Sooperset
Sooperset mcp-atlassian
Vendors & Products Sooperset
Sooperset mcp-atlassian
Type Values Removed Values Added
Description MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers are processed by _process_authentication_headers and used to construct Atlassian fetchers without calling validate_url_for_ssrf. A caller who can set these headers can supply an internal or metadata-service URL and cause the server to send requests to that destination, bypassing the incomplete CVE-2026-27826 remediation. This issue is fixed in version 0.22.0.
Title mcp-atlassian has an incomplete SSRF remediation
Weaknesses CWE-918
References
Metrics cvssV4_0

{'score': 8.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N'}
Weaknesses
  • CWE-918

    Server-Side Request Forgery (SSRF)

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 28, 2026, 5:18 PM
Reserved
Aug 20, 2026, 7:14 PM

View source JSON

Updated
Sep 28, 2026, 5:18 PM

JSON

Status
Analyzed
Published
Sep 22, 2026, 6:17 PM
Modified
Sep 29, 2026, 6:59 PM

View source JSON

No data.

Updated
Sep 22, 2026, 8:15 PM

JSON