A security vulnerability was discovered in the npm lockfile system, which can be exploited to inject malicious modules into packages. The author of the article created a pull request with a malicious package that was easily missed by project owners due to its innocuous name and version. The lockfile generated by npm was not thoroughly reviewed, allowing the malicious code to be injected into the package. This vulnerability highlights the need for careful review of lockfile changes, especially for libraries, where the risk is lower. To mitigate this issue, best practices such as using a linter like lockfile-lint and validating resources served over HTTPS from trusted sources can help reduce the risk of lockfile injection attacks.