CVE-2026-87911

Read-only enforcement bypass enabling operating system command execution in the SQL validation component of Amazon awslabs postgres-mcp-server

State: Published
Severity: 9.0 Critical
Published: Sep 9, 2026
Updated: Sep 10, 2026
Reserved: Sep 9, 2026

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Description

An OS command injection weakness in the read-only enforcement of the SQL validation component in Amazon awslabs postgres-mcp-server before 1.1.7 might allow an unauthenticated actor to execute operating system commands on the host of a self-managed PostgreSQL server by placing a crafted COPY ... TO PROGRAM statement into content that is processed when an authenticated user interacts with the MCP server in its default read-only mode.

To remediate this issue, users should upgrade to version 1.1.7 or later.

Scores

CVSS	Score	Vector	Source
4.0	9.0 Critical	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H	AMZN
3.1	9.6 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H	AMZN

Weaknesses

CWE-78 Improper neutralization of special elements used in an OS command ('OS command injection')
CWE-184 Incomplete list of disallowed inputs

Affected Products

Product	Versions
AWS Labs postgres MCP ServerAWS	before 1.1.7Affected

References

https://pypi.org/project/awslabs.postgres-mcp-server/1.1.7/patch
https://aws.amazon.com/security/security-bulletins/2026-104-aws/vendor-advisory
https://github.com/awslabs/mcp/security/advisories/GHSA-fph8-pg5w-78fvthird-party-advisory

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