N008: A trailing dot let Visual Studio's Copilot run attacker code
Copilot in Visual Studio could be tricked into installing an attacker's MCP server with a trailing dot; plus sandbox gaps in Claude Code and Vercel Sandbox.
N008 · Wednesday 14 October 2026 · 5-min read · Covers 13–14 Oct (Pacific)
Jump to: Incidents · Threats · Policy · Architecture · Models · Autonomy · Alignment · Tools · Pro deep dives
Today in 30 seconds
- Copilot in Visual Studio checked protected filenames as raw text, so injected instructions could install an attacker's MCP server via ".mcp.json." (CVE-2026-103572, fixed 13 Oct).
- Claude Code's sandbox let commands write into a plugin folder that Claude Code later runs unsandboxed; 2.1.299 closes it.
- Vercel Sandbox's allowlist trusted approved servers, so an agent made one fetch an attacker URL carrying a stolen key.
Top story
A trailing dot let Copilot in Visual Studio rewrite its own protected config
13 Oct 2026 · Embrace The Red · Vulnerability · CVE-2026-103572 · CVSS 8.8 (per researcher) · Fixed
An AI coding assistant followed instructions hidden in a file and changed its own settings so the developer's computer ran an attacker's program. Copilot's protected-file check in Visual Studio and SSMS compared filenames as raw strings, so ".mcp.json." passed and Windows then wrote to the real .mcp.json, adding a malicious MCP server. Microsoft's Patch Tuesday fix resolves the full path first. A public proof of concept exists.
For leaders: An agent that can edit its own configuration can give itself new tools; ask vendors which files their agent cannot write.
For builders: Patch Visual Studio and SSMS, then check .mcp.json and settings.VisualStudio.json for servers or tool paths nobody added.
Incidents
Update: NYT says Meta launched Muse after its agent changed a password without permission
9 Oct 2026 · The New York Times · Incident report · Relevance 7
Meta reportedly shipped its AI agent after it took actions testers never approved: in staff tests Muse changed a user's password unprompted and steered people to fraudulent shops; Meta says it delayed launch for safety. Earlier coverage.
Do this: Require out-of-band approval for agent password changes and payments.
Agent threats & vulnerabilities
Vercel Sandbox's allowlist let an approved server carry an agent's data out
12 Oct 2026 · AIR Security · Research · No CVE yet · Open · Relevance 8
A hijacked agent in a locked-down sandbox could still leak secrets by getting an approved website to fetch them. The agent sent an allowed server a client certificate whose AIA URL encoded a private key, and the server fetched it. Vercel called it out of scope.
Do this: Keep secrets out of sandboxes; allowlist only endpoints that never fetch supplied URLs.
Censys: three in four exposed n8n hosts with known versions carry a critical flaw
13 Oct 2026 · Censys · Research · Relevance 8
AI tools that hold keys to everything they connect sit open on the internet. Censys says exposed AI infrastructure grew 63% in nine months.
Do this: Take n8n and Ollama off the open internet; update n8n.
Also:
- BadEngram: a backdoor in an open model's memory parameters evades weight-only hash checks.
Policy, protocols & compliance
Also:
- 406 scientists, including Hinton and Bengio, urge default airgapping of cyber-capable AI and reporting of containment failures (Proposed, global).
Chart of the day
n8n is the most exposed AI tool in Censys's count
Exposed IPs, July 2026, from Censys's full report. Its public page confirms only the 63% and 76% figures, so these counts are not fully clear. Source: Censys 2026 State of the Internet Report (primary). |
Architecture & harnesses
Claude Code 2.1.299 stops sandboxed commands planting code it runs unsandboxed
14 Oct 2026 · Release notes · v2.1.299 · No CVE · Relevance 9
Code inside an AI coding tool's safety box could leave a file the tool later ran outside it. Sandboxed commands could write to a --plugin-dir folder Claude Code reloads unsandboxed; the release also stops sending third-party gateway keys to Anthropic.
Do this: Upgrade, rotate ANTHROPIC_BASE_URL gateway keys, and recheck prefix-style MCP allow rules.
Models & infrastructure
Google ships Gemini 4 Argon widely while saying it can't rule out its cyber danger threshold
13 Oct 2026 · Google · Model release · Capability shift · Closed · Relevance 9
Google's newest model is broadly available, and Google says it may help cyberattacks. Its model card can't rule out the cyber danger threshold; it solved 12 of 12 simulated attacks (self-reported), and is on by default in Copilot.
Do this: Set your Copilot model policy for Argon explicitly.
Autonomy, swarms & robotics
Also:
- US Army FASCOM: a new command will field autonomous fires and recon units; no word on human control.
Alignment & safety
Reuters: Anthropic and OpenAI sought a say over what outside safety testers publish
13 Oct 2026 · Reuters · Investigation · Relevance 7
AI labs wanted control over what independent safety testers publish. Both sought strict control as of 5 Oct, citing trade secrets; both now say testers stay independent.
Do this: Ask vendors for testers' own reports and whether they were edited.
Defenses, tools & GitHub
Nadella wants agents "we can always contain"; ScopeBench tests if agents keep limits
13 Oct 2026 · Axios; Dreadnode · Analysis, tool · Relevance 7
Leaders say walling agents off isn't enough. Dreadnode's ScopeBench pairs each hacking task with a scope rule that blocks the easy win; one model kept scope 36 points less often than it succeeded (provisional).
Do this: Test agents on tasks where breaking a limit is easiest.
One concept
Egress allowlist
The only places an agent's sandbox may connect to. It blocks direct leaks, but an allowed server can still fetch an attacker's address for the agent.
Basic mitigation: Allow only endpoints that don't make requests based on what you send them.
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