Github security concern related to phoenix 1.4 app

Hi everyone,

Today when i opened my email I got this from github:

> Security advisory GHSA-h9rv-jmmf-4pgx (moderate severity) affects 2 repositories:
> serialize-javascript (npm) used in 2 repositories

So i was wondering if the serialize-javascript is a default for phoenix 1.4 apps and what would be the best way to avoid this problem.
also i wanted to report this problem. The verion of phoenix used for this app is phoenix 1.4.11

The repo can be found here Blog API
Thanks in advance for any ideas or suggestions regarding this


You probably need to upgrade your npm packages…

install this…

then, from assets…

$ cd assets
$ ncu -u

and add a babel.config.js file that looks like this

module.exports = api => {

  const presets = [
  const plugins = [

  return {

If you can give similar suggestions that use vanilla npm commands instead, you will help a much larger portion of readers at more skill/comfort/familiarity levels. Giving black-box advice has similar concerns to curl | bash.


$ mix -v
Phoenix v1.4.10
$ mix koko
$ cd koko/assets
$ npm outdated
Package                             Current  Wanted  Latest  Location
copy-webpack-plugin                   4.6.0   4.6.0   5.0.5  global
css-loader                            2.1.1   2.1.1   3.2.1  global
mini-css-extract-plugin               0.4.5   0.4.5   0.8.0  global
optimize-css-assets-webpack-plugin    4.0.3   4.0.3   5.0.3  global
uglifyjs-webpack-plugin               1.3.0   1.3.0   2.2.0  global
webpack                               4.4.0   4.4.0  4.41.2  global
webpack-cli                           2.1.5   2.1.5  3.3.10  global

returns the list of outdated packages, then just update the versions of packages You want in packages.json and run npm install.


Thanks @kokolegorille for showing me that I only had to do an upgrade for my packages.json file.
I use yarn and also ran previously before posting this thread this command yarn upgrade. But it appears that this command will not ignore ranges.
yarn upgrade --latest will install the latest verisons without worrying about the constraints.

Full list of yarn upgrade doc

1 Like

Hi I am having the same problem (getting npm audit warnings about serialize-javascript which is depended on by uglifyjs-webpack-plugin)

Latest version of the deprecated lib uglifyjs-webpack-plugin is 2.2.0 and its package-lock.json specifies dependancy "serialize-javascript": "^1.7.0" which is installed by npm as "version": "1.9.1" .

I have tested this with a newly generated phoenix 1.4.9 project using npm audit after updating uglifyjs-webpack-plugin to 2.2.0 and re-installing all node modules.

What is most strange about this for me is that this uglifyjs-webpack-plugin shouldn’t be appearing at all in our generated projects! See this PR which was merged on 11 Dec 2018. Phoenix 1.4.9 was released on 4 July 2019.

I don’t know why the generated projects are using the deprecated lib still but I fixed it manually by replicating the work done in that PR on my local project. It is very easy - only 3 lines in the whole project need changing. See here:


For anyone who, for whatever reason, wants to stick with the versions specified by Phoenix, but update to the latest compatible minor/patch versions, I’ve found this to be a simple, no-stress approach:

cd "path/to/my_app_web/assets"
rm package-lock.json
rm -rf node_modules
npm install --silent --no-progress

package.json remains unchanged, package-lock.json is updated and can be committed to version control, and, as of today with Phoenix 1.4.16, npm audit finds 0 vulnerabilities.

Here’s a Bash script to perform that for multiple web apps in an umbrella project, to be placed in and run from the umbrella project’s root directory.

#!/usr/bin/env bash
set -o errexit

# Updates npm packages to latest available according to package.json.


bold=$(tput bold)
normal=$(tput sgr0)

# Change directory to that of this script
cd "${0%/*}"

for app in "${web_apps_with_assets[@]}"; do
		echo -e "\n${bold}${app}${normal}"
		cd "apps/${app}/assets"
		rm package-lock.json
		rm -rf node_modules
		npm install --silent --no-progress