CVE-2012-4561: Undefined Security Weakness

The 1 publickeymakedss, 2 publickeymakersa, 3 signaturefromstring, 4 sshdosign, and 5 sshsignsessionid functions in keys.c in libssh before 0.5.3 free "an invalid pointer on an error path," which might allow remote attackers to cause a denial of service crash via unspecified vectors...