eap.c in pppd in ppp 2.4.2 through 2.4.8 has an rhostname buffer overflow in the eap_request and eap_response functions.

Buffer overflow in the rc_mksid function in plugins/radius/util.c in Paul's PPP Package (ppp) 2.4.6 and earlier, when the PID for pppd is greater than 65535, allows remote attackers to cause a denial of service (crash) via a start accounting message to the RADIUS server.

Integer overflow in the getword function in options.c in pppd in Paul's PPP Package (ppp) before 2.4.7 allows attackers to "access privileged options" via a long word in an options file, which triggers a heap-based buffer overflow that "[corrupts] security-relevant variables."

The winbind plugin in pppd for ppp 2.4.4 and earlier does not check the return code from the setuid function call, which might allow local users to gain privileges by causing setuid to fail, such as exceeding PAM limits for the maximum number of user processes, which prevents the winbind NTLM authentication helper from dropping privileges.

BSD pppd allows local users to change the permissions of arbitrary files via a symlink attack on a file that is specified as a tty device.