MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

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Summary

CVECVE-2026-27826
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-10 19:17:20 UTC
Updated2026-04-13 15:01:48 UTC
DescriptionMCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from [email protected]

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

EPSS: 0.000730000 probability, percentile 0.222220000 (date 2026-04-15)

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.2HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
3.1[email protected]Secondary8.2HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Sooperset Mcp Atlassian All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sooperset Mcp-atlassian affected < 0.17.0 Not specified

References

ReferenceSourceLinkTags
github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291... [email protected] github.com Patch
github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9 [email protected] github.com Vendor Advisory, Exploit
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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