MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass

Exploitation

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

CVSS

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

EPSS

• CVE-2026-77243: 0.54% estimated exploitation activity in the next 30 days; percentile 45.72 (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 ENABLEDTOOLS and TOOLSETS filters are enforced at tools/list time only. tools/call dispatches from the full unfiltered tool registry (73 tools). Any user with access to the server endpoint that knows a tool name can invoke it directly. Tool names are not secret since mcp-atlassian is open source. Any direct JSON-RPC call bypasses the restriction entirely. READONLYMODE is not affected: it has dual enforcement at list time (listtoolsmcp) and call time @checkwriteaccess decorator. The developers applied the correct pattern to READONLYMODE but not to ENABLEDTOOLS or toolsets - confirming this is an implementation oversight. Impact Any user with access to the MCP server's HTTP endpoint can invoke any of the 73 registered tools regardless of ENABLEDTOOLS or TOOLSETS configuration - including write and delete operations on Jira issues, Confluence pages, etc. Operators deploying mcp-atlassian via Streamable HTTP rely on ENABLEDTOOLS to enforce least-privilege access; the bypass…

Published by the source

22 Sep 2026, 20:34 UTC

Last modified by the source

1 Oct 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:54 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3r68-hf9h-887v

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-3r68-hf9h-887v

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-3r68-hf9h-887v

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# Patch Next advisory brief: CVE-2026-77243

Advisory: MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass
IDs: CVE-2026-77243, GHSA-3r68-hf9h-887v
Record: https://patchnext.com/advisories/cve-2026-77243 (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 8.8)
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-3r68-hf9h-887v (GitHub-reviewed advisory GHSA-3r68-hf9h-887v lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0)
- Verified: https://osv.dev/vulnerability/GHSA-3r68-hf9h-887v (OSV record GHSA-3r68-hf9h-887v lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0 (fixed))

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