MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77246
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 19:16:48 UTC
Updated2026-09-28 14:31:10 UTC
DescriptionMCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.

Risk And Classification

Primary CVSS: v3.1 8.6 HIGH from [email protected]

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

EPSS: 0.004280000 probability, percentile 0.345480000 (date 2026-09-29)

Problem Types: CWE-22 | CWE-200 | CWE-441 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-200 CWE-200: Exposure of Sensitive Information to an Unauthorized Actor | CWE-441 CWE-441: Unintended Proxy or Intermediary ('Confused Deputy')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
3.1[email protected]Secondary7.4HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
3.1CNADECLARED7.4HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/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/security/advisories/GHSA-wv8v-v4c5-v75j 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Vendor Advisory
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
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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