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High, CVSS 7.1amended

MCP Atlassian: Jira and Confluence attachment upload tools can read arbitrary server-local files

CVE-2026-77253GHSA-vc25-24vv-fxxm

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (mcp-atlassian 0.22.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
EPSS
  • CVE-2026-77253: 0.44% estimated exploitation activity in the next 30 days; percentile 38.67 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary MCP Atlassian exposes Jira and Confluence attachment upload tools that accept arbitrary local filesystem paths and upload those file contents to Atlassian. In HTTP or multi-user deployments, an MCP caller who can invoke write tools can cause the server to read any file accessible to the MCP process and send it to Jira/Confluence as an attachment. Details The Confluence MCP upload tool accepts a filepath described as an absolute or relative server path in src/mcpatlassian/servers/confluence.py:1290-1316 and forwards it directly to confluencefetcher.uploadattachment() in src/mcpatlassian/servers/confluence.py:1356-1363. The multi-upload variant accepts comma-separated local paths in src/mcpatlassian/servers/confluence.py:1372-1449. The Confluence attachment implementation converts relative paths to absolute paths, checks only existence, and then opens the path for upload. There is no call to validatesafepath() or any allowed directory check for uploads in…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-vc25-24vv-fxxm

  2. Revision 2 · amended ·

    Amended from osv record GHSA-vc25-24vv-fxxm

  3. Revision 1 · created ·

    Published from ghsa record GHSA-vc25-24vv-fxxm

Agent brief

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# Patch Next advisory brief: CVE-2026-77253

Advisory: MCP Atlassian: Jira and Confluence attachment upload tools can read arbitrary server-local files
IDs: CVE-2026-77253, GHSA-vc25-24vv-fxxm
Record: https://patchnext.com/advisories/cve-2026-77253 (revision 3, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mcp-atlassian 0.22.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI mcp-atlassian: affected < 0.22.0; fixed in 0.22.0

## Suggested inspection (read-only)
- `python -m pip show mcp-atlassian`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-atlassian.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vc25-24vv-fxxm (GitHub-reviewed advisory GHSA-vc25-24vv-fxxm lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0)
- Verified: https://osv.dev/vulnerability/GHSA-vc25-24vv-fxxm (OSV record GHSA-vc25-24vv-fxxm lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0 (fixed))

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