gotd/td is a T Telegram MTProto API client in Go. Prior to 0.145.1, proto.UnencryptedMessage.Decode in proto/unencrypted_message.go read attacker controlled dataLen from an unauthenticated MTProto unencrypted packet and allocated make([]byte, dataLen) before checking the remaining buffer, allowing remote unauthenticated denial of service through excessive memory allocation and CPU or garbage collection pressure. This issue is fixed in version 0.145.1.

Affected: Go: github.com/gotd/td

### Impact

A remote, unauthenticated attacker can cause excessive memory allocation (and resulting CPU / GC pressure, potentially OOM termination) by sending a crafted unencrypted MTProto packet.

`(*proto.UnencryptedMessage).Decode` read an attacker-controlled 32-bit `dataLen` field and immediately allocated a buffer of that size via `make([]byte, dataLen)` **before** validating that the underlying buffer actually contained that many bytes. A 20-byte packet declaring a ~1.75 GB payload (e.g. `dataLen = 0x70000000`) forces the runtime to provision and zero-initialize a multi-gigabyte heap allocation before the length is rejected.

Unencrypted messages are part of the unauthenticated MTProto handshake path, so no credentials or established session are required to reach the vulnerable code.

Impact is limited to availability; there is no evidence of memory corruption, out-of-bounds access, or code execution.

### Patches

Fixed in **v0.145.1** by validating `dataLen` against the remaining buffer length before allocation (commit `9d5d1f31e`).

### Workarounds

Upgrade to v0.145.1 or later. There is no in-process workaround for affected versions short of avoiding exposure of the unauthenticated MTProto parsing path to untrusted peers.