In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding.

In PuTTY versions before 0.71 on Windows, local attackers could hijack the application by putting a malicious help file in the same directory as the executable.

A remotely triggerable memory overwrite in RSA key exchange in PuTTY before 0.71 can occur before host key verification.

The TFTP server in ExtraPuTTY 0.30 and earlier allows remote attackers to cause a denial of service (crash) via a large (1) read or (2) write TFTP protocol message.

The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.

Multiple untrusted search path vulnerabilities in Putty beta 0.67 allow local users to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse (1) UxTheme.dll or (2) ntmarta.dll file in the current working directory.

Stack-based buffer overflow in the SCP command-line utility in PuTTY before 0.67 and KiTTY 0.66.6.3 and earlier allows remote servers to cause a denial of service (stack memory corruption) or execute arbitrary code via a crafted SCP-SINK file-size response to an SCP download request.

Integer overflow in the terminal emulator in PuTTY before 0.66 allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code via an ECH (erase characters) escape sequence with a large parameter value, which triggers a buffer underflow.

The (1) ssh2_load_userkey and (2) ssh2_save_userkey functions in PuTTY 0.51 through 0.63 do not properly wipe SSH-2 private keys from memory, which allows local users to obtain sensitive information by reading the memory.

PuTTY 0.59 through 0.61 does not clear sensitive process memory when managing user replies that occur during keyboard-interactive authentication, which might allow local users to read login passwords by obtaining access to the process' memory.