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Current spec 2026-07-28

security ·

AWS Labs DocumentDB MCP Server read-only mode bypassed via write-capable aggregation stages

An advisory states that the DocumentDB MCP Server's aggregate tool did not validate pipeline stages for write operations, so an authenticated MCP client could use $out or $merge to write to the connected database while the server was in its default read-only mode. AWS published a security bulletin the same day. A fixed version exists.

GitHub advisory GHSA-j694-4m5j-w8hc, published August 5, states that the DocumentDB MCP Server's aggregate tool did not validate pipeline stages for write operations. An authenticated MCP client could use $out or $merge to write to the connected database while the server was in its default read-only mode. The GHSA record rates it Moderate at CVSS 5.5 (v3.1 vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N). The affected package is awslabs.documentdb-mcp-server on PyPI below 1.0.12, patched at 1.0.12.

NVD lists CVE-2026-18954 published 2026-08-05T20:17:08 with CVSS v4.0 5.7 MEDIUM and CVSS v3.1 5.5 MEDIUM, CWE-863. AWS security bulletin 2026-076-AWS, dated August 5 13:00 PDT, names the same affected and fixed versions and offers read-only database credentials as a workaround; the bulletin does not state a CVSS score.

The advisory is absent from the global GitHub Advisory Database mirror at github.com/advisories/GHSA-j694-4m5j-w8hc (404) and does not appear on the awslabs/mcp advisories listing whose top entry as of the check was dated 2026-07-23.

How was this verified, and what are the sources?

Published · last verified · confidence 0.90.

  1. GitHub repository security advisory record for GHSA-j694-4m5j-w8hc; Published Aug 5 2026, Moderate, CVSS 5.5, package and patched version - accessed
  2. NVD API record for CVE-2026-18954; published field and both CVSS entries - accessed
  3. AWS security bulletin page dated Aug 5 2026; states affected and fixed versions and a credentials workaround, with no CVSS - accessed
  4. Global GHSA mirror returns 404 for this ID - accessed
  5. awslabs/mcp advisories listing, newest entry 2026-07-23 - accessed

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