Hi, I reported a bug against the Debian distribution, but it might be more useful to report it here. Via fuzzing I discovered a key which will cause the ssh-keygen process to segfault when fingerprinting via: ssh-keygen -l -f bogus.key This segfault is a NULL pointer dereference, and is a denial of service attack if you run a service which allows SSH keys to be uploaded and display their fingerprints. (I run such a service. Oops.) There is a simple patch which I've posted in the bug report which fixes the problem for me, but probably needs more eyes. This is the patch: --- sshkey.c.orig 2015-10-13 22:42:26.178252307 +0300 +++ sshkey.c 2015-10-13 22:42:58.781080815 +0300 @@ -1198,6 +1198,9 @@ bits == 0 || bits > SSHBUF_MAX_BIGNUM * 8) return SSH_ERR_INVALID_FORMAT; /* Bad bit count... */ + if ( ret->rsa == NULL ) + return SSH_ERR_INVALID_FORMAT; + /* Get public exponent, public modulus. */ if ((r = read_decimal_bignum(&ep, ret->rsa->e)) < 0) return r; The crasher can be found in the bug-report (note there are two, the second is easier to deal with): https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=801530:w I'm not a member of the list, but I'll keep an eye out for updates, via the archives, for the next few days in case there are questions. Steve -- http://www.steve.org.uk/ _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev