Firefox 59.0.3 – Compatibility update for Windows 10 V1803

[German]Mozilla's developers released an update for the Firefox browser on April 30, 2018. The new version 59.0.3 is a maintenance update, which should improve the compatibility of the browser with Windows 10 April Update (version 1803).

The background for this maintenance update is a bug in JavaScript, where the eval function returns an invalid value when using RegExp. Here is the description of the bug:

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180404171943

Steps to reproduce: The CMS we build websites on has an old script which is using `eval` to dynamically create a `RegExp`, using code like `eval('/~!~/g')` (however, the same issue occurs with any `RegExp`, regardless of content or flags).

An isolated version of this issue is at https://jsbin.com/lurazav/1/edit?js,console

That this issue can/should be worked around by using `new RegExp()` instead of `eval`

Actual results: A `SyntaxError` is thrown, with the message "invalid regular expression flag ÿ"

Expected results: A valid `RegExp` object should be returned from the `eval` call

The bug has been observed under Windows 10 Enterprise, version 1803, OS build 17133.1 (but be present in all Win 10 V1803 builds). Here is a screenshot of the error message.

You can use the web site http://www.dnnsoftware.com/wiki to test Firefox. The bug also affects all Firefox ESR versions from version 52 onwareds.

Firefox 59.0.3 for Linux, macOS, Windows

By default, the update is offered automatically in Firefox – here the notification under Windows 10.

But you can use the menu and the command Help – About Firefox to check for upcoming updates. Only the fixed Windows 10 April update bug is mentioned in the release notes. If you are using Firefox under Windows 10, you should always update it. On this Mozilla FTP site you can download Firefox version 59.0.3 for Linux, macOS and Windows for reinstallation. The download of the German installer or the complete setup file for Windows can be found under the following links:

• Windows 32 Bit
• Windows 64 Bit

Here are the direct download addresses.