MSRXCVE-2026-77265
CVE-2026-77265
MCP Atlassian: SSRF via DNS Rebinding in Header-Based Authentication Flow
CVSS 3.1 · CNA · github.com
chance of exploitation in the next 30 days (EPSS; higher than 21% of CVEs)
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, header-supplied Jira or Confluence URLs are resolved and validated before the HTTP client resolves the hostname again for the connection. An unauthenticated caller can use a DNS-rebinding hostname that returns a public address during validation and an internal address during connection, causing requests to internal or metadata services. The advisory traces the vulnerable input and processing flow through X-Atlassian-Jira-Url, X-Atlassian-Confluence-Url, validate_url_for_ssrf, and DNS rebinding, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
Scores
Affected packages and fixed versions
| Package | Ecosystem | Fixed in |
|---|---|---|
| mcp-atlassian | PyPI | 0.22.0 |
Affected products
- mcp-atlassian mcp atlassian: < 0.22.0
Weakness: CWE-918
Also known as: GHSA-49xv-9743-pw8w, PYSEC-2026-4083
4 references (advisories, patches, write-ups)
- https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 · Patch
- https://github.com/sooperset/mcp-atlassian/pull/1448 · Issue Tracking, Patch
- https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 · Release Notes
- https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-49xv-9743-pw8w · Exploit, Vendor Advisory
Sources: NVD, CVE.org, OSV.dev, FIRST EPSS. Missing ones did not answer or have no record yet.