CVE-2026-77248

CVE-2026-77248 is a high-severity vulnerability in Mcp-atlassian Mcp Atlassian with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Frequently asked questions

What is CVE-2026-77248?
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
How severe is CVE-2026-77248?
CVE-2026-77248 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-77248 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-77248?
CVE-2026-77248 affects Mcp-atlassian Mcp Atlassian. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-77248?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-77248 published?
CVE-2026-77248 was published on 2026-09-22 and last updated on 2026-09-28.

References

Affected products (1)

More vulnerabilities in Mcp-atlassian Mcp Atlassian

All CVEs affecting Mcp-atlassian Mcp Atlassian →

Other CWE-22 (Path Traversal) vulnerabilities

Browse all CWE-22 (Path Traversal) vulnerabilities →