mcp-atlassian: Arbitrary file read via missing path validation in confluence_upload_attachment

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-73498: 0.48% estimated exploitation activity in the next 30 days; percentile 41.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary confluenceuploadattachment passes filepath directly to open(filepath, "rb") with no path validation. Any authenticated MCP client — or an AI agent manipulated via prompt injection — can read any file the server process can access and exfiltrate it to Confluence as an attachment. Details Root cause: src/mcpatlassian/confluence/attachments.py, uploadattachmentdirect(): The fix already exists in the same file. downloadattachment() calls validatesafepath(targetpath). The developer's intent was to validate paths — upload was missed. Proven by the codebase itself. One-line fix — add before the open() call: PoC Stage 1 — Direct API (confirmed): Uploaded C:\Windows\System32\drivers\etc\hosts (826 bytes) → HTTP 200. Uploaded ~/.ssh/ided25519 (SSH private key) → HTTP 200. Stage 2 — End-to-end MCP client (confirmed against v0.21.1): Server opens file and uploads to Confluence without validation. Stage 3 — Prompt injection, no MCP credentials required (confirmed 2026-07-10): Payload…

Published by the source

10 Jul 2026, 19:34 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g5r6-gv6m-f5jv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g5r6-gv6m-f5jv

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# Patch Next advisory brief: CVE-2026-73498

Advisory: mcp-atlassian: Arbitrary file read via missing path validation in confluence_upload_attachment
IDs: CVE-2026-73498, GHSA-g5r6-gv6m-f5jv
Record: https://patchnext.com/advisories/cve-2026-73498 (revision 2, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
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://osv.dev/vulnerability/GHSA-g5r6-gv6m-f5jv (OSV record GHSA-g5r6-gv6m-f5jv lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0 (fixed))
- Verified: https://github.com/advisories/GHSA-g5r6-gv6m-f5jv (GitHub-reviewed advisory GHSA-g5r6-gv6m-f5jv lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0)

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