CVE-2026-77274

HighCVSS 8.2/10Last modified Sep 28, 2026

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_url_for_ssrf has a backslash authority confusion because it interprets the authority differently from the Requests connection layer in the header-based Jira and Confluence URL authentication flow. A crafted URL can validate as an external hostname while the HTTP client connects to an internal host, permitting server-side requests to protected network resources. This issue is fixed in version 0.22.0.

Metrics

CVSS 3.1 8.2/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Weakness enumeration

CWE-918

Affected software

Vendor	Product	Versions
sooperset	mcp-atlassian	< 0.22.0

References

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460Patch
https://github.com/sooperset/mcp-atlassian/pull/1448Issue Tracking, Patch
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0Release Notes
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-hgcf-4mq8-5266Exploit, Vendor Advisory
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-hgcf-4mq8-5266Exploit, Vendor Advisory

Timeline

Published: Sep 22, 2026
Last modified: Sep 28, 2026
NVD status: Analyzed

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