TI-2026-53927 Aliases CVE-2026-77242

MCP Atlassian: Incomplete fix for CVE-2026-27826: DNS rebinding bypasses SSRF validation (validated IP not pinned)

HIGH 66CWE-367Published 2026-09-22 · Updated 2026-09-22

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: High · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_url_for_ssrf checks a hostname's resolved addresses, but Requests and urllib3 resolve the hostname again when connecting. A caller can use a short-lived DNS answer that is public during validation and private during connection, preserving unauthenticated access to internal or metadata endpoints despite the earlier CVE-2026-27826 remediation. The advisory traces the vulnerable input and processing flow through validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.003 22nd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed mcp-atlassian (sooperset): 0.22.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
sooperset	mcp-atlassian	before 0.22.0	0.22.0	Patch available	CNA

mcp-atlassian Vendorsooperset Affected before 0.22.0 Fixed in 0.22.0 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:mcp-atlassian:mcp_atlassian::::::::	before 0.22.0	Vulnerable	Mcp-atlassian

cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* Versions before 0.22.0 Vulnerable ·Mcp-atlassian

Remediation

Fix · CNA mcp-atlassian (sooperset) Fixed in 0.22.0

Timeline

2026-10-02 Threatist record created from CVE-2026-77242

References

Exploit 1

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-72fm-whvq-jghf

Patch 2

Other 1

https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0

TI-2026-53938 MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials CVSS 3.1CRITICAL 9.1
TI-2026-53957 MCP Atlassian: SSRF Protection Bypass CVSS 4.0HIGH 8.8
TI-2026-53935 Protection mechanism failure in sooperset mcp-atlassian CVSS 4.0HIGH 8.3
TI-2026-53946 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
TI-2026-53932 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
TI-2026-22177 Path traversal in sooperset mcp-atlassian CVSS 3.1CRITICAL 9.1

See all 33 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences