The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called `secret_hash` and the other `session_id`. Initially, both of them are the same, but after key re-exchange, previous `session_id` is kept and used as an input to new `secret_hash`. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating `secret_hash` of different size than the `session_id` has. This becomes an issue when the `session_id` memory is zeroized or when it is used again during second key re-exchange.
Created libssh tracking bugs for this issue:
Affects: epel-7 [bug 1998139]
Affects: fedora-all [bug 1998135]
Created libssh2 tracking bugs for this issue:
Affects: epel-8 [bug 1998140]
Affects: fedora-all [bug 1998136]
Created mingw-libssh2 tracking bugs for this issue:
Affects: fedora-all [bug 1998137]
Embargo lifted, patch attached, analysis has been completed resolving..
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2022:2031 https://access.redhat.com/errata/RHSA-2022:2031