Inefficient Regular Expression Complexity in nervjs/taro


Reported on

Sep 2nd 2021

✍️ Description

A ReDoS (regular expression denial of service) flaw was found in the @tarojs/helper package. An attacker that is able to provide crafted input as url may cause an application to consume an excessive amount of CPU.

🕵️‍♂️ Proof of Concept

Create the following poc.mjs

// PoC.mjs

import pkg from '@tarojs/helper';
const {REG_URL} = pkg;
var time =;
var time_cost = - time;
console.log("Time taken to validate : " + time_cost+" ms")

Execute the following command in another terminal:

npm i @tarojs/helper
node poc.js

Check the Output:

Time taken to validate : 44880 ms

💥 Impact

This vulnerability is capable of exhausting system resources and leads to crashes. Ideally, validation should be done within 1-10 milliseconds, but in the above case, it's 44 seconds.

We created a GitHub Issue asking the maintainers to create a a year ago
ready-research submitted a
a year ago
a year ago


After applying the patch output is Time taken to validate : 4 ms

a year ago


@admin It seems maintainers recommending submitting an issue using If we open an issue directly in GitHub, the bot will automatically closing that issue. Can you please look into this?

a year ago


Hey ready-research, thanks for making us aware of this.

Strange form as there is no field for leaving an email.

Here's my suggestion. Fill out the form and ask them to email and CC yourself in the final text field. This way, should they respond, we can both stay in the loop.

Does that sound reasonable to you?

chenjiajian validated this vulnerability a year ago
ready-research has been awarded the disclosure bounty
The fix bounty is now up for grabs
chenjiajian confirmed that a fix has been merged on acadb6 a year ago
ready-research has been awarded the fix bounty
constants.ts#L107 has been validated
Jamie Slome
a year ago


CVE published! 🎉

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