mcp-atlassian: Arbitrary server-side file read via attachment upload

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-2026-73496: 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 A client that can invoke MCP tools can read arbitrary files from the server host and exfiltrate them as Atlassian attachments. The attachment-upload tools take a client-supplied filepath and open() it on the server's filesystem. The upload tools are meant to attach a file from the caller's environment — the client supplies a path expecting it to refer to its own machine. Over a remote transport (HTTP/SSE) that path is instead resolved and read on the server, and the tool offers no way for the client to send file content in place of a server-side path. A remote client therefore reads the server's files — and, in multi-tenant deployments, other tenants' data — instead of its own. (In a local stdio deployment the server runs as the user, so the path refers to the user's own files and reading any path is the intended behavior; the exposure is specific to remote/multi-user transports.) Details The upload tools read a client-supplied path directly on the server: -…

Published by the source

10 Jul 2026, 19:34 UTC

Last modified by the source

18 Sep 2026, 11:56 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wm45-qh3g-v83f

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-wm45-qh3g-v83f

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# Patch Next advisory brief: CVE-2026-73496

Advisory: mcp-atlassian: Arbitrary server-side file read via attachment upload
IDs: CVE-2026-73496, GHSA-wm45-qh3g-v83f
Record: https://patchnext.com/advisories/cve-2026-73496 (revision 2, source checked 26 Oct 2026, 13:46 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-wm45-qh3g-v83f (OSV record GHSA-wm45-qh3g-v83f lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0 (fixed))
- Verified: https://github.com/advisories/GHSA-wm45-qh3g-v83f (GitHub-reviewed advisory GHSA-wm45-qh3g-v83f lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0)

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