CVE-2026-77261: MCP Atlassian: SSRF redirect protection missing for basic-auth and OAuth authentication branches
_make_ssrf_safe_hook() blocks HTTP redirects to private/internal IPs by validating the Location header before the client follows a 3xx response. The problem is that this hook is only attached in one of three authentication branches — the header-PAT path. Basic auth and OAuth branches skip it entirely, so if the connected Atlassian server returns a redirect to something like http://169.254.169.254/, the requests session follows it without complaint.
This is an incomplete fix for GHSA-7r34-79r5-rcc9. The hook works fine when it’s there — it just isn’t there for most production auth configurations.
References
- github.com/advisories/GHSA-6529-c226-h328
- github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
- github.com/sooperset/mcp-atlassian/pull/1448
- github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0
- github.com/sooperset/mcp-atlassian/security/advisories/GHSA-6529-c226-h328
- nvd.nist.gov/vuln/detail/CVE-2026-77261
Code Behaviors & Features
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