CVE-2026-18953

HIGH

Improper limitation of a pathname to a restricted directory in aws-transform-mcp-server

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-18953. PoCs published by ronamosa.

AI-analyzed exploit summary This PoC demonstrates an arbitrary file write vulnerability (CWE-22) in awslabs.aws-transform-mcp-server versions 0.1.0-0.1.4, where the `validate_write_path()` function fails to confine writes to a base directory, allowing attackers to write files outside the intended sandbox via absolute paths or path traversal. The PoC includes both vulnerable and fixed versions of the validation logic for comparison.

Description

Improper limitation of a pathname to a restricted directory in the get_resource tool in Amazon awslabs.aws-transform-mcp-server 0.1.0 through 0.1.4 might allow a context-dependent actor to write arbitrary files outside the intended working directory via the savePath parameter. To remediate this issue, users should upgrade to version 0.1.5 or later.

Exploits (1)

github WORKING POC
by ronamosa · pythonpoc
https://github.com/ronamosa/CVE-2026-18953

This PoC demonstrates an arbitrary file write vulnerability (CWE-22) in awslabs.aws-transform-mcp-server versions 0.1.0-0.1.4, where the `validate_write_path()` function fails to confine writes to a base directory, allowing attackers to write files outside the intended sandbox via absolute paths or path traversal. The PoC includes both vulnerable and fixed versions of the validation logic for comparison.

Classification
Working Poc 100%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: awslabs.aws-transform-mcp-server 0.1.0-0.1.4
No auth needed
Prerequisites: Ability to invoke the `get_resource` tool with attacker-controlled `savePath` and `fileName` parameters (e.g., via prompt injection in an LLM agent using the MCP server)
mistral-large-3 · analyzed Aug 08, 2026 Full analysis →

Scores

CVSS v3 8.6
EPSS 0.0015
EPSS Percentile 4.6%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-22
Status published
Products (1)
AWS/aws-transform-mcp-server 0.1.0 - 0.1.4
Published Aug 05, 2026
Tracked Since Aug 06, 2026