1895277 - Windows Firefox Kerberos authentication broken with Extended protection set to allow on ADFS server with a SHA384 SSL certificate

Status: VERIFIED FIXED

(Core :: Networking, defect, P2)

Description

[Mervyn Morris]

Steps to reproduce:

1. Upgrade ADFS Communication and SSL certificate to SHA384
2. Verify that ExtendedProtectionCheck is set to Allow on the ADFS service. Get-AdfsProperties| select ExtendedProtectionTokenCheck
3. From a Domain Joined Windows client attempt to access a SAML configured website using Windows Firefox from internal network.

Actual results:

User is greeted with a prompt for username and password.
Manually entering the username and password fails and leads to the same prompt from the ADFS server.

Similar to https://bugzilla.mozilla.org/show_bug.cgi?id=1179722 but specific only when using SHA384 certificate.

Expected results:

The user should have been directed to the ADFS server and complete the authentication using Windows Integrated Authentication.
User should have then been redirected to the website with the appropriate authentication and access

Comment 1

[Mervyn Morris]

https://support.mozilla.org/en-US/questions/1440307

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Security: PSM' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:keeler, could you have a look please?

For more information, please visit BugBot documentation.

Comment 4

[Randell Jesup [:jesup] (needinfo me)]

Mike - how important would this be to enterprises?

Comment 5

[Mike Kaply [:mkaply]]

I think it will be more of an issue as more folks roll out Extended Protection, so it definitely is important for enterprise.

It looks like bug 1179722 was the same issue, but they ended up reverting back to 256 temporarily.

Comment 6

[Kershaw Chang [:kershaw]]

This feels quite important. I’ll give this bug a higher priority and hope to see it resolved soon.

Comment 8

[Mervyn Morris]

Just for reference because of other issues we were finally forced to upgrade to a SHA384 certificate for our adfs/ identity server. This has effectively broken functionality on Firefox now.

Comment 9

[matthias.huijgen]

My organization is also forced to temporarily downgrade to SHA256 for our ADFS server. After 1-1-2026 we are forced to use SHA384, so please resolve this as soon as possible.

Comment 10

[Valentin Gosu [:valentin] (he/him)]

I think this comment may point to the culprit:
https://searchfox.org/mozilla-central/rev/270c20e4b063d80ce71f029b4adc4ba03a12edc0/extensions/auth/nsAuthSSPI.cpp#366-383

// Start hashing. We are always doing SHA256, but depending
// on the certificate, a different alogirthm might be needed.
nsAutoCString hashString;

nsresult rv;
nsCOMPtr<nsICryptoHash> crypto;
crypto = do_CreateInstance(NS_CRYPTO_HASH_CONTRACTID, &rv);
if (NS_SUCCEEDED(rv)) rv = crypto->Init(nsICryptoHash::SHA256);
if (NS_SUCCEEDED(rv))
  rv = crypto->Update((unsigned char*)mCertDERData, mCertDERLength);
if (NS_SUCCEEDED(rv)) rv = crypto->Finish(false, hashString);
if (NS_FAILED(rv)) {
  free(mCertDERData);
  mCertDERData = nullptr;
  mCertDERLength = 0;
  free(sspi_cbt);
  return rv;
}

Comment 11

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1895277 - Update nsAuthSSPI to check certificate hash algorithm r=keeler

Comment 12

[Valentin Gosu [:valentin] (he/him)]

Hi Mervyn,

Could you check with this build and let me know if it fixes your issue when ExtendedProtection is on and off?
https://treeherder.mozilla.org/jobs?repo=try&revision=f5df60eedb97ab95c9cdf53a96a6f36510a0f589&selectedTaskRun=dZpd6YjXTQWpIm4Lw8o4Mg.0
Click on Artifacts and Debugging Tools and download either the installer setup.exe or the portable archive target.zip

Thanks!

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/74448667aef1
https://hg.mozilla.org/integration/autoland/rev/192526d25deb
Update nsAuthSSPI to check certificate hash algorithm r=keeler

Comment 14

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/192526d25deb

Comment 15

[Mike Kaply [:mkaply]]

Is this able to be backported to the ESR?

Comment 16

[Valentin Gosu [:valentin] (he/him)]

(In reply to Mike Kaply [:mkaply] from comment #15)

Is this able to be backported to the ESR?

Yes, it grafts cleanly to esr140.
I'd prefer to wait for confirmation the fix works before uplifting.

Comment 17

[Valentin Gosu [:valentin] (he/him)]

Confirmed working by Steve Rast via email. Will request uplift to ESR.

I am also affected. I tested now with 144.0b2 and can confirm that the login to ADFS with the new SHA384 certificate is working.

Comment 18

[Phabricator Automation]

firefox-esr140 Uplift Approval Request

• User impact if declined: Failure to log into Active Directory Federation Services when the SSL certificate uses SHA384
• Code covered by automated testing: no
• Fix verified in Nightly: yes
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: Ideally QE would be necessary, but I'm not sure if anyone in QA has access to an active directory setup
• Risk associated with taking this patch: low
• Explanation of risk level: Aready confirmed working by reporters.
• String changes made/needed: None
• Is Android affected?: no

Comment 19

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1895277 - Update nsAuthSSPI to check certificate hash algorithm r=keeler

Original Revision: https://phabricator.services.mozilla.com/D262779

Comment 20

[Mervyn Morris]

Good day.

Sorry it took so long to respond.

I have successfully tested Nightly 143.0a1 (2025-09-03) (64-bit) and verified that the issue is resolved when accessing a website using ADFS with a SHA384 ADFS certificate.

Comment 21

[Valentin Gosu [:valentin] (he/him)]

(In reply to Mervyn Morris from comment #20)

I have successfully tested Nightly 143.0a1 (2025-09-03) (64-bit) and verified that the issue is resolved when accessing a website using ADFS with a SHA384 ADFS certificate.

Thank you! 🙏 We really appreciate your help with this one!

Comment 22

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr140/rev/4f7ad536599f