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Description of problem:
When NSS server receives Client Hello with signature_algorithms extension that doesn't list any algorithms that it understands, it doesn't abort the connection but continues and signs the Server Key Exchange message with sha1+rsa algorithm.
Version-Release number of selected component (if applicable):
nss-3.27.1-13.el6.x86_64
How reproducible:
always
Steps to Reproduce:
1. Send client hello that lists only RSA-PSS signature algorithms and PFS ciphersuites
Actual results:
Server responds with Server Hello, Certificate and so on
Expected results:
handshake_failure alert
Additional info:
This is in direct violation of RFC 5246 MUST clause:
If the client does not support the default algorithms (...),
it MUST send the
signature_algorithms extension, listing the algorithms it is willing
to accept.
("default algorithms" refers to sha1+rsa, sha1+dsa and sha1+ecdsa pairs)
If the client has offered the "signature_algorithms" extension, the
signature algorithm and hash algorithm MUST be a pair listed in that
extension. Note that there is a possibility for inconsistencies
here. For instance, the client might offer DHE_DSS key exchange but
omit any DSA pairs from its "signature_algorithms" extension. In
order to negotiate correctly, the server MUST check any candidate
cipher suites against the "signature_algorithms" extension before
selecting them. This is somewhat inelegant but is a compromise
designed to minimize changes to the original cipher suite design.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHEA-2018:1865
Description of problem: When NSS server receives Client Hello with signature_algorithms extension that doesn't list any algorithms that it understands, it doesn't abort the connection but continues and signs the Server Key Exchange message with sha1+rsa algorithm. Version-Release number of selected component (if applicable): nss-3.27.1-13.el6.x86_64 How reproducible: always Steps to Reproduce: 1. Send client hello that lists only RSA-PSS signature algorithms and PFS ciphersuites Actual results: Server responds with Server Hello, Certificate and so on Expected results: handshake_failure alert Additional info: This is in direct violation of RFC 5246 MUST clause: If the client does not support the default algorithms (...), it MUST send the signature_algorithms extension, listing the algorithms it is willing to accept. ("default algorithms" refers to sha1+rsa, sha1+dsa and sha1+ecdsa pairs) If the client has offered the "signature_algorithms" extension, the signature algorithm and hash algorithm MUST be a pair listed in that extension. Note that there is a possibility for inconsistencies here. For instance, the client might offer DHE_DSS key exchange but omit any DSA pairs from its "signature_algorithms" extension. In order to negotiate correctly, the server MUST check any candidate cipher suites against the "signature_algorithms" extension before selecting them. This is somewhat inelegant but is a compromise designed to minimize changes to the original cipher suite design.