CVE-2026-77246

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to…

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.

Vendor: mcp-atlassian
Product: mcp atlassian
CVSS 3.1: 8.6 (high), scored by NVD (primary)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
CVSS 3.1: 7.4 (high), scored by security-advisories@github.comCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
CWE: CWE-22, CWE-200, CWE-441
Published: 2026-09-22
NVD modified: 2026-09-28
NVD status: Analyzed

Not in the CISA KEV catalogue at the last update.

EPSS

0.43% chance of exploitation in the next 30 days (percentile 35th)

FIRST EPSS, updated 17 Oct 2026. About EPSS

CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.

References

github.com (Patch)
github.com (Issue Tracking, Patch)
github.com (Release Notes)

Data last updated 18 Oct 2026. Sources: NVD API 2.0, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.