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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77242
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 18:17:16 UTC
Updated2026-09-29 15:41:42 UTC
DescriptionMCP 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

EPSS: 0.002930000 probability, percentile 0.196310000 (date 2026-09-29)

Problem Types: CWE-367 | CWE-918 | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mcp-atlassian Mcp Atlassian All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sooperset Mcp-atlassian affected < 0.22.0 Not specified

References

ReferenceSourceLinkTags
github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 [email protected] github.com Release Notes
github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c28... [email protected] github.com Patch
github.com/sooperset/mcp-atlassian/security/advisories/GHSA-72fm-whvq-jghf 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Vendor Advisory
github.com/sooperset/mcp-atlassian/pull/1448 [email protected] github.com Issue Tracking, Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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