CVE-2026-10666 in zephyr
Summary
by MITRE • 07/12/2026
parse_ipv4() in subsys/net/ip/utils.c (reached via net_ipaddr_parse() for strings of the form "a.b.c.d:port") copies the port substring into a fixed 17-byte stack buffer (char ipaddr[NET_IPV4_ADDR_LEN + 1]) using a length of str_len - end - 1, where str_len is the full, unbounded input length and end is only the (<=15-byte) offset of the ':' delimiter. Because the destination size is never consulted, a crafted address string with a long suffix after the colon (e.g. "1.2.3.4:" followed by hundreds of bytes) causes an out-of-bounds stack write whose length and contents are fully attacker-controlled (memcpy of the suffix plus a trailing NUL), enabling memory corruption and at minimum a denial of service, and potentially control-flow hijack. The parser is reached from the standard socket API (zsock_getaddrinfo / literal-address resolution), DNS server-string configuration, and the eswifi Wi-Fi co-processor DNS-response path, so an application that resolves a network-influenced address string is exposed. The bug was introduced when the parser was added (Zephyr v1.9.0) and shipped in all releases through v4.4.0. The fix removes the unbounded copy and validates the port length before copying into a small dedicated buffer. Note: the equivalent IPv6 "[addr]:port" path in parse_ipv6() retains the same unbounded copy at this commit and remains a separate, still-reachable instance of the defect.
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Analysis
by VulDB Data Team • 07/12/2026
The vulnerability described represents a critical stack-based buffer overflow in the Zephyr RTOS network parsing functionality that affects versions 1.9.0 through 4.4.0. This issue stems from improper bounds checking during IPv4 address string parsing, specifically when handling addresses in the format "a.b.c.d:port". The flaw exists in the parse_ipv4 function within subsys/net/ip/utils.c and is triggered through the net_ipaddr_parse() interface that processes literal IP addresses with port specifications. When a malformed input string containing an excessively long suffix after the colon delimiter is processed, the code performs an unbounded memory copy operation into a fixed 17-byte stack buffer without validating the source length against the destination capacity.
The technical implementation of this vulnerability relies on the function's failure to consult the actual destination buffer size during copy operations. The code calculates the copy length as str_len - end - 1 where str_len represents the complete input string length and end denotes the position of the colon delimiter, which can be at most 15 bytes for valid IPv4 addresses. This calculation ignores the fixed 17-byte buffer constraint, allowing attacker-controlled data to overflow beyond the intended bounds. The vulnerability manifests as a memcpy operation that copies the port suffix plus a trailing null terminator into a buffer that cannot accommodate arbitrarily long input data, creating a classic out-of-bounds write condition.
The operational impact of this vulnerability extends across multiple network processing paths within the Zephyr system, making it particularly dangerous for embedded applications. The affected parsing function serves as a core component in standard socket API operations through zsock_getaddrinfo calls, DNS server string configuration mechanisms, and the eswifi Wi-Fi co-processor's DNS response handling path. Any application that processes network-influenced address strings becomes vulnerable to this attack vector, potentially exposing systems to both denial of service conditions and more severe memory corruption exploits. The vulnerability's reach is amplified by its inclusion in the base networking stack that handles fundamental connectivity operations.
The exploitability of this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which classifies such issues under improper input validation and buffer management practices. From an ATT&CK framework perspective, this represents a memory corruption technique (T1059.007) that can lead to privilege escalation through process injection or control-flow hijacking. The vulnerability's persistence across multiple Zephyr releases since version 1.9.0 indicates a systemic issue in the codebase's input validation approach, making it particularly concerning for long-term deployments. The fact that an equivalent IPv6 parsing function (parse_ipv6) retains the same unbounded copy behavior demonstrates that this is a broader architectural problem affecting the entire network parsing subsystem.
The recommended mitigation strategy involves implementing proper bounds checking before any memory copy operations and validating port string lengths against predetermined buffer limits. The fix should ensure that the destination buffer capacity is consulted during copy operations, preventing oversized data from being written beyond allocated boundaries. Additionally, input sanitization measures should be implemented to reject excessively long port specifications, and the code should utilize safe string handling functions that automatically enforce bounds checking. The security patch must also address the IPv6 variant of this vulnerability to provide comprehensive protection against similar memory corruption attacks across both IP protocol versions.