Arbitrary Code Execution in Language Servers for AWS Workspace MCP Configuration Handling
CVE-2026-12957 is a high-severity improper trust boundary enforcement vulnerability in Language Servers for AWS before version 1.65.0 on all supported platforms, affecting Amazon Q Developer integrations. The issue arises from unsafe handling of workspace-controlled project configuration, specifically MCP server configuration files such as .amazonq/mcp.json. When a user opens a maliciously crafted workspace and trusts it when prompted, the language server may automatically load attacker-controlled configuration and execute commands defined within the project configuration files. Reported technical context indicates the spawned processes can inherit the developer’s environment, exposing credentials and tokens present in the session. The vulnerability therefore enables arbitrary command execution in the context of the local developer environment.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
16 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity vulnerability in Amazon Q Developer plugins/language server where workspace-embedded configuration files could be auto-executed without user permission, enabling attacker-controlled command execution and theft of cloud credentials and API keys from a developer environment.
A high-severity flaw in Amazon Q Developer / Language Servers for AWS that allowed a malicious repository to define an MCP server via .amazonq/mcp.json, leading to command execution and theft of developer cloud credentials after the workspace was trusted.
A high-severity arbitrary code execution vulnerability in the Amazon Q Developer Extension for VS Code caused by automatic loading and execution of workspace MCP server configurations without user consent, combined with inherited environment variables that could expose cloud credentials.
A high-severity arbitrary command execution vulnerability in Amazon Q for Visual Studio Code caused by automatically loading and executing MCP server configurations from a repository's .amazonq/mcp.json file without user consent or workspace trust checks, potentially exposing cloud credentials and other secrets.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.