backpack/crud is vulnerable to Cross-Site Scripting (XSS)

Impact

It’s a “moderate” vulnerability… but being an admin panel, take this seriously. It’s difficult… but an attacker could conduct a targeted phishing campaign, in order to trick your users or admins to click a malicious link, which under very specific circumstances could give them information... or even admin access. It’s unlikely, but that’s not good enough in admin panels - It should be made impossible. That’s why you are bothered with this.

Patches

If you don’t have custom error views, the views provided by Backpack would output the exception message without escaping it, which made an attack possible using Reflected XSS, in some very specific circumstances (that we will not disclose). To fix those error views in Backpack 4.x and 5.x, please run:

composer update backpack/crud
php artisan backpack:fix

The problem has been patched in:

• v4.0.63
• v4.1.69
• v5.0.13

IMPORTANT! Running a composer update should get you the patched version, but you also need to run php artisan backpack:fix afterwards, to patch your published error views, if necessary.

Workarounds

Alternatively (if you don’t want to run composer update), you can manually look inside your error views in “resources/views/errors” and output e($exception->getMessage()) instead of $exception->getMessage(). That’s all there is to the fix, really.

What the maintainers have done about this

Acted as soon as our team found it (last week of March 2022):

• Pushed patches to 5.x, 4.1 and 4.0;
• Made it easy to apply the fix to existing projects, using a new php artisan backpack:fix command;
• Kept the specific circumstances a secret; as far as they know, only the maintainer's team knows about the niche case where this exploit is possible;
• Emailed all our licensed users, to have a chance to fix their projects before it’s public;
• Sent an email blast to our 25.000+ strong Security Newsletter;
• Made this public with a blog post and soon a CVE, after our community has had a reasonable chance to fix their projects;
• Will continue to monitor this and remind paying users to apply this fix if they haven’t;

For more information

If you have any questions or comments about this advisory:

• Open an issue in backpack/crud
• Email us at hello@backpackforlaravel.com

PS. You can read this blog post for more information.