Webpack version 4.39.1 is a patch release following version 4.39.0, both being iterations of the popular JavaScript module bundler. Developers focusing on stability and incremental improvements will find these versions appealing. A key difference lies in the "dist" section of the package data: version 4.39.1 exhibits a slightly increased unpacked size (1,441,204 bytes) compared to 4.39.0 (1,441,130 bytes). This suggests minor internal adjustments, bug fixes, or performance tweaks rather than significant feature additions. The release date of 4.39.1 is also slightly later (2019-08-02) than the previous version (2019-08-01), which reinforces the idea of a quick follow-up release to address any immediate issues found in 4.39.0.
For developers already using webpack 4, upgrading to 4.39.1 should be a relatively safe and straightforward process. The dependency and devDependency lists remain identical, indicating no breaking changes or major updates to underlying tools. While the description across both versions is the same, highlighting webpack's core functionality of bundling CommonJs/AMD modules and supporting various loaders for file preprocessing, the subtle differences in size and release date point towards a focus on refining the existing feature set and ensuring a reliable developer experience. Therefore, it's advisable for webpack users to stay updated with the latest patch releases within their major version, as they often contain important fixes and optimizations.
All the vulnerabilities related to the version 4.39.1 of the package
Regular Expression Denial of Service (ReDoS) in micromatch
The NPM package micromatch prior to version 4.0.8 is vulnerable to Regular Expression Denial of Service (ReDoS). The vulnerability occurs in micromatch.braces() in index.js because the pattern .* will greedily match anything. By passing a malicious payload, the pattern matching will keep backtracking to the input while it doesn't find the closing bracket. As the input size increases, the consumption time will also increase until it causes the application to hang or slow down. There was a merged fix but further testing shows the issue persisted prior to https://github.com/micromatch/micromatch/pull/266. This issue should be mitigated by using a safe pattern that won't start backtracking the regular expression due to greedy matching.
Uncontrolled resource consumption in braces
The NPM package braces fails to limit the number of characters it can handle, which could lead to Memory Exhaustion. In lib/parse.js, if a malicious user sends "imbalanced braces" as input, the parsing will enter a loop, which will cause the program to start allocating heap memory without freeing it at any moment of the loop. Eventually, the JavaScript heap limit is reached, and the program will crash.
