MCP Atlassian: Incomplete fix for CVE-2026-27826: redirect-based SSRF via unhooked requests session in Jira user-permission lookup

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77249
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 19:16:49 UTC
Updated2026-09-29 18:59:49 UTC
DescriptionMCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, JiraUserMixin._lookup_user_by_permissions uses the module-level requests.get function instead of the fetcher's protected session. A caller-controlled public Jira URL can redirect that unhooked request to an internal address, bypassing the redirect checks added for CVE-2026-27826. The advisory traces the vulnerable input and processing flow through JiraUserMixin._lookup_user_by_permissions, requests.get, self.jira._session.get, 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 5.3 MEDIUM from [email protected]

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

EPSS: 0.003330000 probability, percentile 0.240600000 (date 2026-09-29)

Problem Types: CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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/pull/1448 [email protected] github.com Issue Tracking, Patch
github.com/sooperset/mcp-atlassian/security/advisories/GHSA-v9m3-wfh8-5646 [email protected] github.com Exploit, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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