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Mozilla Firefox does not work when disabling the encryption key TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014)

  • 7 uphendule
  • 1 inale nkinga
  • Igcine ukuphendulwa ngu dkeeler

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Dear Mozilla team,

We are a company that develops web systems. The customer’s security service asks us to close all old encryption keys on the server in order to avoid system vulnerabilities and use only new keys. We disabled most of the old keys and the system works fine on all browsers. As soon as we turn off the encryption key TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014), then all web systems stop working through the Mozilla Firefox browser. (At the same time, everything works correctly on other browsers). The Mozilla Firefox Documentation says that this browser supports new encryption keys and can work without old encryption keys. Link ( Also on our server are included all the necessary encryption keys for Mozilla Firefox to work.

Do you have any ideas on how to solve this?

All Replies (7)

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You can check the server.

You can check your browser for compatible cipher suites.

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Thanks, but unfortunately we`ve checked it and it didn't work.

Screenshot 1 shows that system didn't work with Mozilla browser Screenshot 2 shows that after we opened SHA1 Mozilla works with old keys that need to be changed and all other browsers work on new keys.

We have other sets but Mozilla also didn't work with them.

Do you have any other ideas on how to solve this?

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What cipher suites does your server enable?

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Hi, @dkeeler We use those

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I think that what dkeeler means is a full list of cipher suites that are enabled on the server. I sounds that you only have this single cipher suite enabled that Firefox supports and other enabled cipher suites aren't supported by Firefox.

See also:

Okulungisiwe ngu cor-el

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I think it is a little confusing to refer to encryption ciphers as keys. Your private key is used to generate your SSL certificate, and you can change that key and generate new certificates without disabling any ciphers.

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Hi Yulyan, if I'm understanding what you're indicating correctly, your server does enable at least one cipher suite that Firefox enables. Can you open a new bug here: with as much detail as you can include? Thanks!