LimeSurvey version: LimeSurvey Community Edition Version 6.15.13+250923 
Own server or LimeSurvey Cloud: own, shared hosting php version 7.4
Survey theme/template: default
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After today's update nothing works in the interface. If I try to change a setting or set any option in configuration I get 

The CSRF token could not be verified

apparently the error is generated in /vendor/yiisoft/yii/framework/web/CHttpRequest.php 
on line
1400 throw new CHttpException(400,Yii::t('yii','The CSRF token could not be verified.'));

How do I work around this. It was not what I expected from a securuty update.

Thanks for your help with this frustration.

Running into same problem on our installation.
We need a rollback feature...

I see in the patch notes:
-Fixed issue #20271: [security] Reflected XSS in CSRF token handling (#4449) (Gabriel Jenik)

But i'm not clear on what has changed there yet.

I am sorry for the problem. We just released a new version. Please update.

Thanks for the swift reply.
Just noticed the update coming in, unfortunately ComfortUpdate is broken as well so i'm going to update manually now and report back.

Edit:
Comfortupdate worked in an incognito window. (?)
And the update indeed fixed the issue.

Login was not possible.
After update manually, it works again

I confirm, the update works. I had to use the trick of logging in from incognito window (which may be a useful technique to remember), otherwise I got this same error page during the login, which meant LS could not be used at all. Thanks for fixing this