Pre-Auth EAP-TLS DoS on SoftEther VPN Developer Edition

SoftEtherVPN is a an open-source cross-platform multi-protocol VPN Program. In 5.2.5188 and earlier, a pre-authentication denial-of-service vulnerability exists in SoftEther VPN Developer Edition 5.2.5188 (and likely earlier versions of Developer Edition). An unauthenticated remote attacker can crash the vpnserver process by sending a single malformed EAP-TLS packet over raw L2TP (UDP/1701), terminating all active VPN sessions.

An authentication bypass vulnerability exists in the CiRpcServerThread() functionality of SoftEther VPN 5.01.9674 and 4.41-9782-beta. An attacker can perform a local man-in-the-middle attack to trigger this vulnerability.

An information disclosure vulnerability exists in the CtEnumCa() functionality of SoftEther VPN 4.41-9782-beta and 5.01.9674. Specially crafted network packets can lead to a disclosure of sensitive information. An attacker can send packets to trigger this vulnerability.

An information disclosure vulnerability exists in the ClientConnect() functionality of SoftEther VPN 5.01.9674. A specially crafted network packet can lead to a disclosure of sensitive information. An attacker can perform a man-in-the-middle attack to trigger this vulnerability.

SoftEtherVPN 5.02.5187 is vulnerable to Use after Free in the Command.c file via the CheckNetworkAcceptThread function. NOTE: the Supplier disputes this because the use-after-free is not in the VPN software, but is instead in a separate tool that has no untrusted input and runs under the user's own privileges (it is a stress-testing tool for a networking stack).

SoftEther VPN 5.02.5187 is vulnerable to Buffer Overflow in Internat.c via the UniToStrForSingleChars function. NOTE: the Supplier disputes this because the behavior only enables a local user to attack himself through the UI,

Memory Leak vulnerability in SoftEtherVPN 5.02.5187 allows an attacker to cause a denial of service via the UnixMemoryAlloc function. NOTE: the Supplier disputes this because the behavior is limited to a single allocation of a few hundred bytes with a command-line tool.

SoftEther VPN 5.02.5187 is vulnerable to Buffer Overflow in the Command.c file via the PtMakeCert and PtMakeCert2048 functions. NOTE: the Supplier disputes this because the behavior only allows a user to attack himself by typing a long string on a command line.

An authentication bypass vulnerability exists in the CiRpcAccepted() functionality of SoftEther VPN 4.41-9782-beta and 5.01.9674. A specially crafted network packet can lead to unauthorized access. An attacker can send a network request to trigger this vulnerability.

A heap-based buffer overflow vulnerability exists in the vpnserver WpcParsePacket() functionality of SoftEther VPN 4.41-9782-beta, 5.01.9674 and 5.02. A specially crafted network packet can lead to arbitrary code execution. An attacker can perform a man-in-the-middle attack to trigger this vulnerability.

A denial-of-service vulnerability exists in the vpnserver ConnectionAccept() functionality of SoftEther VPN 5.02. A set of specially crafted network connections can lead to denial of service. An attacker can send a sequence of malicious packets to trigger this vulnerability.

A denial-of-service vulnerability exists in the vpnserver EnSafeHttpHeaderValueStr functionality of SoftEther VPN 5.01.9674 and 5.02. A specially crafted network packet can lead to denial of service.

A denial of service vulnerability exists in the DCRegister DDNS_RPC_MAX_RECV_SIZE functionality of SoftEther VPN 4.41-9782-beta, 5.01.9674 and 5.02. A specially crafted network packet can lead to denial of service. An attacker can perform a man-in-the-middle attack to trigger this vulnerability.

An integer underflow vulnerability exists in the vpnserver OvsProcessData functionality of SoftEther VPN 5.01.9674 and 5.02. A specially crafted network packet can lead to denial of service. An attacker can send a malicious packet to trigger this vulnerability.

See.sys, up to version 4.25, in SoftEther VPN Server versions 4.29 or older, allows a user to call an IOCTL specifying any kernel address to which arbitrary bytes are written to.