MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path
MCP 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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-77246
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 8 Nov 2026, 02:13 UTC · Revision 1
Source evidence
MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path
core-osv · Original sourcePublished 22 Sept 2026, 18:51 UTC
MCP 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.
osv:CVE-2026-77246
Complete source record
{
"id": "ebb6dcd396095a6208ac66edcfa55dd8daca9216c0f83260933ce0cedffe0c21",
"url": "https://osv.dev/vulnerability/CVE-2026-77246",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path",
"summary": "MCP 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.",
"evidence": "osv:CVE-2026-77246",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-77246",
"aliases": [
"CVE-2026-77246",
"GHSA-wv8v-v4c5-v75j",
"PYSEC-2026-4104"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/sooperset/mcp-atlassian",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "b041733473f95119dd539542a43c280737a8e460"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "0.22.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "b041733473f95119dd539542a43c280737a8e460"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "b041733473f95119dd539542a43c280737a8e460"
}
],
"source": "REFERENCES_TAG",
"original_tag": "v0.22.0"
},
{
"cpe": "cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "0.22.0"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v0.21.1",
"v0.21.0",
"v0.20.1",
"v0.20.0",
"v0.19.0",
"v0.18.1",
"v0.18.0",
"v0.17.0",
"v0.16.1",
"v0.16.0",
"v0.15.0",
"v0.14.3",
"v0.14.2",
"v0.14.1",
"v0.14.0",
"v0.13.1",
"v0.13.0",
"v0.12.0",
"v0.11.12",
"v0.11.11",
"v0.11.10",
"v0.11.9",
"v0.11.8",
"v0.11.7",
"v0.11.6",
"v0.11.5",
"v0.11.4",
"v0.11.3",
"v0.11.2",
"v0.11.1",
"v0.11.0",
"v0.10.6",
"v0.10.5",
"v0.10.4",
"v0.10.3",
"v0.10.2",
"v0.10.1",
"v0.10.0",
"v0.9.0",
"v0.8.4",
"v0.8.3",
"v0.8.2",
"v0.8.1",
"v0.8.0",
"v0.7.1",
"v0.7.0",
"v0.6.5",
"v0.6.4",
"v0.6.3",
"v0.6.2",
"v0.6.1",
"v0.6.0",
"v0.5.0",
"v0.4.0",
"v0.3.1",
"v0.3.0",
"v0.2.6",
"v0.2.5",
"v0.2.4",
"v0.2.3",
"v0.2.2",
"v0.2.1",
"v0.2.0",
"v0.1.16",
"v0.1.15",
"v0.1.14",
"v0.1.13",
"v0.1.12",
"v0.1.11",
"v0.1.10",
"v0.1.8",
"v0.1.7",
"v0.1.6",
"v0.1.5",
"v0.1.4"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77246.json"
}
}
],
"modified": "2026-10-28T02:30:52.879811770Z",
"provider": "osv",
"references": [
"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77246.json",
"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j",
"https://nvd.nist.gov/vuln/detail/CVE-2026-77246",
"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460",
"https://github.com/sooperset/mcp-atlassian/pull/1448"
],
"provider_metadata": {
"cwe_ids": [
"CWE-200",
"CWE-22",
"CWE-441"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77246.json"
}
},
"related_cves": [
{
"value": "CVE-2026-77246",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 521681,
"published_at": "2026-09-22T18:51:54.54+00:00"
}