upgraded openssh from 4.3_p2-r1 to 4.3_p2-r3 this morning, and was immediately unable to communicate with remote cvs servers. did not change ~/.ssh/config, CVSROOT, CVS_RSH, or anything else related to ssh or cvs. nothing was changed on the remote ends, and everybody else could use cvs from their machines (all non-gentoo) just fine. but "cvs diff" from this machine would just sit there until a few minutes later it timed out. downgraded to openssh 4.3_p2-r1 and was able to run "cvs diff" against the remote server just fine again. local system is gentoo, was running cvs 1.12.12-r2, openssh 4.3_p2-r3, remote system was fedora core 5 running cvs 1.11.17, openssh 3.9p1.
So re-emerge cvs.
emerged the latest openssh, re-emerged cvs, then tested it using "cvs diff filename" and am now able to communicate with remote cvs servers successfully.
OK, closing then. Thanks for reporting back.