CVE-2026-77249: MCP Atlassian: Incomplete fix for CVE-2026-27826: redirect-based SSRF via unhooked requests session in Jira user-permission lookup
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, JiraUserMixin.lookupuserbypermissions uses the module-level requests.get function instead of the fetcher's protected session. A caller-controlled public Jira URL can redirect that unhooked request to an internal address, bypassing the redirect checks added for CVE-2026-27826. The advisory traces the vulnerable input and processing flow through JiraUserMixin.lookupuserbypermissions, requests.get, self.jira.session.get, and makessrfsafehook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
MCP Atlassianto a version that resolves this vulnerability.Fixed in 0.22.0
Event History
Frequently Asked Questions
Which deployments are affected?
MCP Atlassian deployments running a version prior to 0.22.0 are affected where Jira user-permission lookup can process a caller-controlled public Jira URL.
What does an attacker need to exploit this issue?
An attacker needs to supply or control a public Jira URL that redirects to an internal address. The vulnerable permission-lookup path follows that redirect through an unprotected module-level requests.get call.
Are existing SSRF redirect protections sufficient?
No. The affected lookup path does not use the fetcher's protected session, so it bypasses the redirect checks implemented in _make_ssrf_safe_hook for the earlier issue.
How can this be remediated?
Upgrade MCP Atlassian to version 0.22.0, which fixes the issue.