CVE-2026-77255

high

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

Vendor / product: Mcp-atlassian — mcp atlassian

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementation without workspace validation. A caller can make the MCP server read arbitrary local files and attach them to a Jira issue, using the server as a confused deputy to exfiltrate the contents. The advisory traces the vulnerable input and processing flow through jira update_issue, attachments, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS

8.6

8.6 (CVSS v3.1)

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

Severity source: NVD CVSS v3.1 (security-advisories@github.com)

Timeline (UTC)

Published: 2026-09-22 19:16

Modified: 2026-09-29 13:41

NVD status: Analyzed

Last synced 2 days ago

Verified against the source API 2026-10-27 06:55 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

mcp-atlassian / mcp_atlassian <0.22.0

Weakness classification (CWE)

CWE-22 CWE-441

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc

Patch / mitigation: https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460

Patch / mitigation: https://github.com/sooperset/mcp-atlassian/pull/1448

References

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/pull/1448 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc 134c704f-9b21-4f2e-91b3-4a467353bcc0

Data sources

NVD CVE API 2.0 — fetched 2026-10-27 06:55 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores

CVE-2026-77255

Affected products

Weakness classification (CWE)

Mitigation & advisories

References

Data sources

Learn the basics

Related CVEs