Eclipse Foundation NetX Duo vulnerabilities

The NetX Secure DTLS server sends a HelloVerifyRequest carrying a freshly generated cookie, but never checks the cookie a client returns. The ClientHello parser copies the client's cookie bytes over the value the server issued, and the server then decides whether the client has been verified from the cookie's length alone. A peer that puts any single cookie byte in its first ClientHello skips the verification exchange entirely, so the server has no return-routability check and completes handshakes for forged source addresses.

`_nx_secure_x509_parse_signature_data` computes the certificate signature's length as `tlv_length - 1` without first checking that `tlv_length` is non-zero. A certificate whose signature is an empty ASN.1 BIT STRING therefore parses successfully and leaves the certificate holding a signature length of `0xFFFFFFFF` and a signature pointer one byte past the end of the buffer. Certificates are parsed from the peer during the TLS handshake, so the input is remote and unauthenticated.

MQTT WebSocket setter ABI mismatch may disclose memory or cause a crash

The NetX Duo MQTT client leaks the packet carrying a malformed PUBLISH message. Each malformed PUBLISH costs one packet, or one chain of packets, from the network driver's receive pool, and nothing returns it. A peer that can deliver a few dozen such messages exhausts the pool and stops all inbound network traffic on the device until it is rebooted.

When NetX Secure is built with `NX_SECURE_KEY_CLEAR`, every TLS record sent on an active session is wiped after it has been handed to TCP. By then the TCP layer owns the packet chain and may already have released it to the packet pool. The wipe therefore writes zeros into packets that are free or in use by another thread, and when a reused packet's pointers no longer describe the old data, the length of the wipe underflows and it runs past the end of the packet pool.

The `_nx_secure_x509_asn1_tlv_block_parse()` function parses ASN.1 TLV (tag-length-value) blocks out of DER-encoded data. It is the primitive underneath all X.509 certificate parsing in NetX Secure, and therefore runs on certificates supplied by a remote peer during the TLS handshake. The function reads the one-byte ASN.1 tag from the caller's buffer *before* checking that the buffer holds at least one byte. When a caller passes a remaining length of zero, the guard correctly returns `NX_SECURE_X509_ASN1_LENGTH_TOO_LONG`, but the read has already happened one byte past the end of the buffer. code: nx_secure/src/nx_secure_x509_asn1_tlv_block_parse.c ``` UINT _nx_secure_x509_asn1_tlv_block_parse(const UCHAR *buffer, ULONG *buffer_length, USHORT *tlv_type, USHORT *tlv_tag_class, ULONG *tlv_length, const UCHAR **tlv_data, ULONG *header_length) { UINT current_index; USHORT current_tag; ULONG length; ULONG length_bytes; current_index = 0; current_tag = buffer[current_index]; /* <-- read before the bounds check */ if (*buffer_length < 1) { return(NX_SECURE_X509_ASN1_LENGTH_TOO_LONG); } ``` The remainder of the function is correctly ordered. The multi-byte length path is guarded by `length_bytes > 4 || length_bytes > *buffer_length` before its read loop, the decoded value is checked against `length > *buffer_length`, and the second single-byte length read follows its own `*buffer_length < 1` guard. The tag read is the only load placed ahead of its check.

Two client-side TLS/DTLS handshake parsers in NetX Secure read fields from a server-supplied message before validating that the message is long enough to contain them. Both are bounded out-of-bounds reads on a remotely reachable path, both are reached from a TLS or DTLS client connecting to a malicious or malformed server, and both have the same shape: the bounds check exists and returns the correct status, but it runs after the read it is meant to guard.

hey, `_nx_snmp_utility_object_id_get` in the NetX Duo SNMP addon does not validate the claimed OID data length against the actual buffer size when the OID uses BER multibyte length encoding, so a remote attacker can send a crafted SNMP packet with a multibyte OID length larger than the available buffer, causing the parser to read past the packet buffer boundary into adjacent heap memory. the OOB bytes are decoded as OID component values and written into the agents internal OID string buffer, corrupting agent state. on systems with memory protection the OOB read poses the risk of crashing the SNMP agent thread, causing denial of service. on bare metal embedded systems without memory protection the read silently succeeds and corrupts the agents internal state with heap data.

`_nx_icmpv6_validate_options()` scans the option area with `while (length > 2)` (`common/src/nx_icmpv6_validate_options.c:79`). An area whose size leaves a one- or two-byte residue exits the loop with that tail unexamined; the residue is not negative, so the function returns `NX_SUCCESS`. Its zero-length rejection never sees those bytes. Every consumer then re-walks the same area, reading a two-byte option header at the residue and subtracting `nx_icmpv6_option_length << 3` with no zero check and no remaining-length check. Three outcomes follow, selected by bytes the attacker controls. **Zero length byte.** The walker subtracts zero and advances zero. All four handlers loop forever — `_nx_icmpv6_process_ra` (`nx_icmpv6_process_ra.c:245, :528`), `_nx_icmpv6_process_ns` (`:251, :329`), `_nx_icmpv6_process_na` (`:147, :156`) and `_nx_icmpv6_process_redirect` (`:247, :350`). The walk runs in the IP thread, which is the highest-priority thread and does not yield inside the loop, so the system stops until a watchdog reset and the frame can be replayed after each one. **Non-zero length byte on a short residue.** The three unsigned counters underflow — `2 - 8` becomes `0xFFFFFFFA` — and the walk continues past the packet buffer, reading until it faults or meets a zero length byte and freezes. The Router Advertisement counter is signed and exits cleanly in this case. **One-byte residue.** The walker reads a two-byte option header, over-reading one byte. During a runaway walk, stray bytes parsing as a link-layer address option are copied into the neighbor cache (`nx_icmpv6_process_ns.c:280, :293`) and subsequently used as the destination MAC for frames to that neighbour, placing off-packet memory on the link. Confirmed by inspection, not reproduced.

The TFTP server accepts a DATA datagram of any size. The dispatcher rejects datagrams shorter than four bytes (nxd_tftp_server.c:1037) and nothing anywhere checks an upper bound, in particular not against the protocol maximum of 4 + NX_TFTP_FILE_TRANSFER_MAX. Two things follow from that one missing check, both reachable before any authentication because TFTP has none. The handler passes `nx_packet_length - 4` straight to FileX: ```c /* addons/tftp/nxd_tftp_server.c:1863, 1889 */ status = nx_packet_copy(packet_ptr, &temp_ptr, server_ptr -> nx_tftp_server_packet_pool_ptr, NX_WAIT_FOREVER); ... fx_file_write(&(client_request_ptr -> nx_tftp_client_request_file), packet_ptr -> nx_packet_prepend_ptr + 4, packet_ptr -> nx_packet_length - 4); ``` `nx_packet_length` is the length of a chain, not of one contiguous buffer, so FileX copies past the end of the first packet: ``` ERROR: AddressSanitizer: heap-buffer-overflow READ of size 1280 at 0x621000001108 thread T5 #0 __interceptor_memcpy #1 _fx_utility_memory_copy filex/common/src/fx_utility_memory_copy.c:78 0x621000001108 is 0 bytes to the right of 4104-byte region ``` Those bytes are written into the file the attacker is uploading, and a TFTP read request hands them back, so this is a memory disclosure with a convenient retrieval channel. The same datagram also wedges the server. `nx_packet_copy` at :1863 needs ceil(nx_packet_length / pool_payload) packets and asks for them with NX_WAIT_FOREVER, so when the attacker sizes the datagram beyond what the pool holds, the server thread suspends and never returns. A liveness probe after one such datagram times out with the pool at 0 of 12 packets and the server thread suspended, and no later client is served. Reject `nx_packet_length > 4 + NX_TFTP_FILE_TRANSFER_MAX` in the DATA branch before either call, and use a bounded wait rather than NX_WAIT_FOREVER for the copy.

On the first DTLS ClientHello, the parser copies a device-claimed session_id length and validates the ciphersuite-list length against the total record length instead of the remaining bytes. An unauthenticated peer drives an OOB source read of up to 255 bytes, and those bytes are echoed verbatim into the outgoing ServerHello, disclosing adjacent process memory over the network. The crash variant fires on the first packet.

In NextX Duo before 6.4.4, in the HTTP client module, the network support code for Eclipse Foundation ThreadX, the parsing of HTTP header fields was missing bounds verification. A crafted server response could cause undefined behavior.

In NetX Duo before 6.4.4, the networking support module for Eclipse Foundation ThreadX, there was a potential out of bound read issue in _nx_icmpv6_validate_options() when handling a packet with ICMP6 options.