topic Re: Harmony Endpoint Firefox browser plugin corrupting XML files in Endpoint

Harmony Endpoint Firefox browser plugin corrupting XML files

Ben_Dunkley — Thu, 19 Dec 2024 15:58:09 GMT

I'm seeing a slightly odd issue with the harmony browser plugin in Firefox when viewing XML documents.

For example, trying to look at SAML metadata XML files (e.g. https://login.microsoftonline.com/common/FederationMetadata/2007-06/FederationMetadata.xml)

In testing across 3-4 different client devices, both Chrome and Edge rendered the document correctly while the Harmony plugin is active, whereas in Firefox, if the Harmony plugin is active all the XML tags get stripped out resulting in a mostly unreadable document.

There is no change when disabling all plugins/extensions apart from Harmony, but the issue goes away as soon as the Harmony plugin is disabled (by launching a private window).

Both the 'view source' and 'inspect' options do appear as expected.

(We're seeing this in current versions of both Firefox 128 ESR and 133, and with plugin version 990.100.834 and endpoint version e88.32).

Any thoughts?

Or just log it with TAC?

Thanks,

Ben

Re: Harmony Endpoint Firefox browser plugin corrupting XML files

Ben_Dunkley — Thu, 19 Dec 2024 15:59:42 GMT

Also - the correct page rendering does show up for a very brief time (~ quarter of a second or so), before being replaced by the unreadable version.

Re: Harmony Endpoint Firefox browser plugin corrupting XML files

PhoneBoy — Thu, 19 Dec 2024 20:47:17 GMT

TAC is probably going to need to investigate.

Re: Harmony Endpoint Firefox browser plugin corrupting XML files

Ben_Dunkley — Fri, 20 Dec 2024 09:46:52 GMT

Fair enough - that'll be a task for next year then!

Thanks 🙂

Re: Harmony Endpoint Firefox browser plugin corrupting XML files

wizard_pl — Wed, 19 Aug 2026 06:06:44 GMT

Hi PhoneBoy,

Just wanted to confirm this issue is still occurring on a current setup — same symptom as originally described (blank page for XML/WSDL content in Firefox, content only visible via View Page Source, works fine in Chrome/Edge, and correct rendering returns in a private window with the extension not permitted there).

Environment where it reproduces:

OS: Microsoft Windows 11 Enterprise, Version 10.0.26200, Build 26200 (corporate managed endpoint)
Harmony Web Protection extension version: 990.106.104
Firefox versions tested: 140.13.0 (ESR) and 153.0.4 — both affected

Interestingly, this problem does not occur on other one computer with the same builds; I don't know what it depends on.

Re: Harmony Endpoint Firefox browser plugin corrupting XML files

jorgeluiznim — Wed, 19 Aug 2026 14:12:27 GMT

I could not reproduce this on the current Recommended client. On Harmony Endpoint 89.10.0370 (Recommended), that exact link (https://login.microsoftonline.com/common/FederationMetadata/2007-06/FederationMetadata.xml) renders correctly in Firefox, Chrome and Edge with the Web Protection extension active. Combined with @wizard_pl noting it does not happen on another machine with the same builds, this looks version or config dependent rather than universal, which is worth pinning down before or alongside a TAC case.

A few things that would help narrow it, if you can share them:

The exact Harmony Endpoint client version on the affected machine, not just the extension build. You listed extension 990.106.104 and Firefox 140 ESR / 153, but the client version is usually the piece that matters here.
Confirmation of what you are doing and where it works: is it only Firefox that strips the tags while Chrome and Edge are fine on the same machine with the same file, and is it any XML/WSDL or only specific ones.
A screenshot of the corrupted rendering, so we can see exactly how the tags are stripped.

For evidence and logs:

From the browser extension, use “Collect event logs” in the Harmony Endpoint extension popup (the button at the bottom of the panel).
From the client, open the client UI, go to the Logging section, “Collect additional information for technical support”, and click Collect to generate a client cpinfo.

One concrete test: since it renders fine on the current Recommended client, update the affected machine to the latest Check Point Recommended version and re-test the same file in Firefox. If it clears up, it was fixed or config related; if it persists, you now have a clean cpinfo plus extension logs to hand to TAC.

If you can gather those, share them here and we can try to help narrow what differs between the affected machine and the one that works. @PhoneBoy is right that this may still need TAC, but that package makes their job much faster.