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CVE-2026-73497

MCP Atlassian is a Model Context Protocol (MCP): DNS-rebinding TOCTOU bypass of the SSRF fix (CVE-2026-27826): unauthenticated SSRF to cloud metadata

MEDIUM
6.5
CVSS Score
Published: September 14, 2026 at 07:50 PM UTC
Updated: September 30, 2026 at 05:51 PM UTC
1 product affected across 1 vendorAtlassian Mcp Atlassian

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). From 0.17.0 until 0.22.0, validate_url_for_ssrf resolves the attacker-controlled X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url header host once at middleware time, but the outbound request is built with the raw hostname and resolves it again at connection time with no IP pinning. An attacker-controlled DNS-rebinding name can return a public IP during validation and 169.254.169.254 or another internal IP during connection, enabling unauthenticated server-side requests to cloud metadata or internal services. The flaw spans src/mcp_atlassian/utils/urls.py, src/mcp_atlassian/servers/main.py, and src/mcp_atlassian/servers/dependencies.py; validate_url_for_ssrf returns only a verdict rather than a pinned IP, UserTokenMiddleware processes the attacker-controlled headers before fetcher creation, and the Jira and Confluence fetchers use the raw hostname. This issue is fixed in version 0.22.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Atlassian Mcp Atlassian· Sooperset
60%
v < 0.22.0
Affected range stops below 0.22.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (4)

x_refsource_CONFIRM
Source: cverecord
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-489g-7rxv-6c8q
x_refsource_MISC
Source: cverecord
https://github.com/sooperset/mcp-atlassian/pull/1448
x_refsource_MISC
Source: cverecord
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
x_refsource_MISC
Source: cverecord
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-918

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