Javascript API SafeExamBrowser object not being set consistently

[ntbutler-nbcs]

Describe the Bug
We've noticed some inconsistent behaviour when trying to do config key verification using the Javascript API. We've just implemented verification via this method instead of the browser headers, and we're deploying a new .seb file to our loan devices.

When launching SafeExamBrowser with the new config, we were inconsistently seeing errors from our system that the configuration key could not be verified. After tweaking things we were able to narrow down the issue to the javascript object "SafeExamBrowser" (and therefore SafeExamBrowser.security) were 'undefined'.

Excerpt from the verification page:

(function () { 
    function verify() {
            document.getElementById('progressInfo').innerHTML += '.'
            if (typeof SafeExamBrowser === 'undefined') {
                redirectToWarning('SEB undefined');
                return;
            }
            if (typeof SafeExamBrowser.security === 'undefined') {
                redirectToWarning('SEB.security undefined');
                return;
            }
           return verifyConfig(SafeExamBrowser.security);
    }
    
    document.addEventListener('DOMContentLoaded', verify);

}());

Error message from our verification page:

After quitting the browser and immediately re-launching, the verification tests pass and we reach the login system of our examination platform. We've seen this behaviour on a number of separate devices - e.g. out of 30 devices (all running Windows 64bit SEB 3.10.1 with the same .seb file), around 8-10 experienced this issue.

Steps to Reproduce
(inconsistent) Steps to reproduce the behavior:

1. Install seb file to C:\ProgramData\SafeExamBrowser\SebClientSettings.seb
2. Launch SafeExamBrowser
3. Launch page tests to see if (typeof SafeExamBrowser === 'undefined')
4. If true, quit browser and relaunch, and test again which seems to work the second time

Expected Behavior
(typeof SafeExamBrowser === 'undefined') should not return true when the page is loaded inside SafeExamBrowser

Version Information

• OS: Windows 11 Education 24H2
• SEB-Version Windows 64bit 3.10.1

Additional Context

Log files from two clients that exhibited this issue
2026-04-17_11h15m35s_Client.zip

2026-04-17_09h48m26s_Client.zip

SEB config file:
SebClientSettings.zip

[dbuechel]

Thanks for the extensive report. I'll have a look at the issue and will try to reproduce it in the upcoming days. Right off the top of my head, this may be a concurrency issue, as some of the key calculations may take a while, and potentially also only on first run.

@danschlet Should the above supposition turn out to be true, then we (or at least I on Windows) would need to change the API to work asynchronously by e.g. returning a JavaScript promise.

[ntbutler-nbcs]

Hi @dbuechel - just an update in case it's helpful, we've seen this occur on a few laptops where we've confirmed things were working using one (active directory) domain account, but then experienced the issue when a different AD account logged in. As before, closing out of SEB and re-launching got around the issue for now.

[dbuechel]

Thanks for the update. Due to the issues with the runtime integrity verification in version 3.10.2, I'm afraid that this will have to wait a bit. But we'll let you know once we had a chance to have a look at the issue.