GHSA-mfv2-4wvm-9pgp: mcp-atlassian (CVE-2026-77266)

Package	Ecosystem	Affected	Fixed in
mcp-atlassian	PyPI	<0.22.0	0.22.0

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The mcp-atlassian package, versions before 0.22.0, has a path traversal flaw in its Jira and Confluence upload_attachment tools: the file_path parameter is opened without the path validation used on download. An authenticated MCP client can therefore make the server read arbitrary files it can access, such as system files or stored tokens, and upload them to the Atlassian instance as attachments. Upgrade to mcp-atlassian 0.22.0 or later, which contains the fix.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.5	Medium	3.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0050, the 43rd percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:09 UTC First seen by agentprime
31 Oct 2026, 14:09 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.