Ian Lewis Ian Lewis

Ian Lewis

Engineer in Tokyo

© 2025 Ian Lewis

TIL: September 29, 2025 - Weekly Reading: Security, Programming, and AI
Sep 28, 2025

Security

  • From MCP to Shell – Stephen Xu, Cayden Liao, Raymond, Jayden

    Yet another method for exploiting Model Context Protocol (MCP) servers to get arbitrary code execution on the local machine. This seems to be mostly an issue for remote MCP servers since a malicious MCP servers installed locally would just be able to run arbitrary code anyway.

    In this case it’s a fairly straightforward vulnerability due to lack of OAuth redirect URL validation. But I think it’s going to be pretty hard to securely use MCP servers in general. MCP servers will be able to return content that can cause the client to try to execute commands locally by design. Clients like Claude Code will ask users to approve the command but I think this is a fairly weak security measure.

  • uv security advisory: ZIP payload obfuscation – William Woodruff

    A security vulnerability (CVE-2025-54368) was found in uv that allows malicious ZIP files to be crafted in a way that makes different tools extract different content from the ZIP archive.

    The vulnerability takes advantage of an ambiguities in the ZIP file format specification, which allows for multiple ways to parse a ZIP file and extract its contents.

Programming

  • (1*2)/2 = 2/2 = 1 – Sam Rose

    This is a fun article that explains the concept of Big-O notation with cool visualizations and simple examples. It covers the basics of time complexity, common Big-O notations, and goes over some examples using some simple sorting and searching algorithms.

  • Default Methods in Go – Miguel Young de la Sota

    Miguel points out that, due to how Go’s interfaces work, it’s not easy to create default methods for interface types that can be inherited by their implementing types.

    He also brings up that to cast an interface to another interface, the runtime must check that all the methods of the target interface are implemented by the original interface. This results in an O(n) operation, where n is the number of methods in the target interface.

    I think this is a good point to consider when designing APIs in Go. Overreliance on interfaces can lead to performance issues and code that’s difficult to maintain. Since the Go community generally prefers to maintain backwards compatibility it’s a good idea to think about the long-term implications of interface design up front.

  • Shopify, pulling strings at Ruby Central, forces Bundler and RubyGems takeover – Joel Drapper

    After David Heinemeier Hansson (DHH) was given a keynote slot at RailsConf 2025, Sideqik withdrew their $250k/year sponsorship of Ruby Central. That left Ruby Central heavily reliant on Shopify for funding. Shopify smelled blood in the water and decided to leverage their position to instigate a takeover of Ruby Central as well as the RubyGems and Bundler projects. Long time contributors were locked out of the projects (at least temporarily), with some, like the original author of Bundler André Arko, singled out to be removed permanently.

    RubyGems and Bundler are supposed to be community-driven projects separate from Ruby Central but their repositories are in the rubygems GitHub organization that’s controlled by Ruby Central. This allowed for the full take over from the organization level. I’m not sure how well they have been covering themselves legally but it’s hard for me to imagine Shopify’s lawyers approving of this kind of thing without legal rationale. All around, this is a terrible look for Shopify and Ruby Central.

Artificial Intelligence