CVE-2026-77261

MCP Atlassian: SSRF redirect protection missing for basic-auth and OAuth authentication branches

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, _make_ssrf_safe_hook is omitted from JiraFetcher and ConfluenceFetcher sessions created through the basic-auth and oauth_pat branches. If an attacker-controlled or compromised configured Atlassian instance returns a redirect to an internal address, those sessions can follow the redirect without revalidating its destination. This issue is fixed in version 0.22.0.

Affected

sooperset · mcp-atlassian

CVSS v3.1 NVD

8.5 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

CVSS v3.1 GITHUB

7.1 HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N

EPSS

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

Published

2026-09-22

Updated

2026-09-23

Proof-of-concept exploits (1)

• advisories/GHSA-6529-c226-h328

Security advisories

• sooperset/mcp-atlassian/security/advisories/GHSA-6529-c226-h328
• sooperset/mcp-atlassian/pull/1448

References

• CVE Record
• NVD entry