Re: The scheme https s not consistent with the TLS enabled setting (Re: [ANN] Apache Tomcat 11.0.22 Available)

On 12/05/2026 14:40, Mark Thomas wrote:
> On 12/05/2026 14:15, Rémy Maucherat wrote:
>> On Tue, May 12, 2026 at 1:46 PM Mark Thomas <[email protected]> wrote:
>>>
>>> On 12/05/2026 09:36, Thomas Meyer wrote:
>>>>
>>>> Zitat von Mark Thomas <[email protected]>:
>>>>
>>>> Hi,
>>>>
>>>>> - Various HTTP/2 validation improvements and a broader change to use
>>>>>    stream resets rather than connection closures where appropriate.
>>>>
>>>> After upgrading our applications to tomcat 11.0.22 we see only
>>>> connection errors 503 for our setup.
>>>>
>>>> We do run Tomcat behind istio/envoy proxy and tomcat uses h2c mode.
>>>> Istio Service mash handles TLS and Tomcat speaks clear text http2.
>>>>
>>>> We see those error messages in our logs: "Connection [{0}], Stream
>>>> [{1}], The scheme [{2}] is not consistent with the TLS enabled setting
>>>> of [{3}]"
>>>>
>>>> which seems to come from this change:
>>>> https://github.com/apache/tomcat/commit/96817a0
>>>>
>>>> Bug or feature?
>>>
>>> Hmm. The change was intentional. The motivation was a security review
>>> that highlighted that clients could connect over h2c to a resource that
>>> required TLS. We rejected that as a vulnerability since the attacker can
>>> only harm their own privacy but we did opt to fix the behaviour to
>>> protect users from client side error / misconfiguration.
>>>
>>> I think the change is consistent with RFC 9113 but there is a reference
>>> to RFC 9112 3.3 which in turn references a "trusted gateway" which is
>>> the case you describe. However, Tomcat currently has no way to determine
>>> (without additional configuration) if an HTTP/2 request is from a
>>> trusted gateway or not.
>>>
>>> Tomcat normally uses the RemoteIpValve in situations where the
>>> application needs to see the protocol used by the client irrespective of
>>> the protocol used between the proxy and Tomcat.
>>>
>>> How practical is it to configure your proxy to use http for :scheme and
>>> have it set the X-Forwarded-Proto header? You'd also need to configure
>>> the RemoteIpValve Tomcat on Tomcat?
>>>
>>> Another solution would be to use h2 rather than h2c between the proxy
>>> and Tomcat.
>>>
>>> On balance I'm leaning towards the new behaviour of requiring some
>>> explicit configuration if proxying secure traffic over h2c. I'll note
>>> that if you proxy over http you'll need similar configuration although
>>> AJP (which only supports clear text) will allow this without further
>>> configuration.
>>>
>>> All that said, I am open to being convinced to either revert the new
>>> behaviour or make it optional.
>>
>> We (kind of) allow this in a way: the connector has a secure flag
>> where it can be configured to say it is supposed to be secure. That is
>> why you have to configure both sslenabled and secure on the connector
>> when actually enabling a secure setup.
> 
> True. Although those only apply to HTTP and can only be used to force 
> http to be treated as https.
> 
> RemoteIpValve is arguably a better, more generic solution.
> 
> You got me thinking about maybe removing those settings from the Connector.

It has been a couple of weeks without any further comment. With the June 
release window approaching now would be the time to make a case 
adjusting this behaviour. Options include:

- do nothing (keep the new behaviour)
- revert the change
- make the change optional (with a configuration option - TBD)
- remove the secure and scheme settings entirely (and use RemoteIpValve)
- something else

I don't think I have strong views on any particular option. Do nothing 
is my default option but only because I can;t see a strong argument for 
on option over any of the others.

Mark