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._lookup_user_by_permissions 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._lookup_user_by_permissions, requests.get, self.jira._session.get, and _make_ssrf_safe_hook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Affected

sooperset · mcp-atlassian

CVSS v3.1 GITHUB

5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

0.32% chance of exploitation in the next 30 days, 24th percentile

Published

2026-09-22

Proof-of-concept exploits (1)

• advisories/GHSA-v9m3-wfh8-5646

Security advisories

• sooperset/mcp-atlassian/security/advisories/GHSA-v9m3-wfh8-5646
• sooperset/mcp-atlassian/pull/1448

References

• CVE Record
• NVD entry