ZephyrProject Zephyr up to 4.4.x DHCPv4 Client Helper dhcpv4.c net_dhcpv4_msg_type_name msg_type out-of-bounds

Summaryinfo

A vulnerability was found in ZephyrProject Zephyr up to 4.4.x. It has been declared as critical. This affects the function net_dhcpv4_msg_type_name of the file subsys/net/lib/dhcpv4/dhcpv4.c of the component DHCPv4 Client Helper. Such manipulation of the argument msg_type leads to out-of-bounds. This vulnerability is traded as CVE-2026-10773. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in ZephyrProject Zephyr up to 4.4.x. It has been rated as critical. Affected by this issue is the function net_dhcpv4_msg_type_name of the file subsys/net/lib/dhcpv4/dhcpv4.c of the component DHCPv4 Client Helper. The manipulation of the argument msg_type with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

The DHCPv4 client helper net_dhcpv4_msg_type_name() in subsys/net/lib/dhcpv4/dhcpv4.c indexes a static 8-element const char * name table after a faulty bounds check. The guard used msg_type <= sizeof(name) instead of msg_type <= ARRAY_SIZE(name); sizeof returns the byte size of the pointer array (32 on 32-bit, 64 on 64-bit targets) rather than the element count of 8, so message-type values from 9 up to that byte size pass the check and cause name[msg_type - 1] to read past the end of the array. The msg_type value originates from the DHCP MESSAGE TYPE option, which is read as an unchecked raw byte from a received packet (net_pkt_read_u8) and passed unmodified into the lookup. A DHCP server, or any host able to inject a spoofed DHCP reply onto the client's link, can therefore drive the index out of bounds. The out-of-range slot yields a garbage const char * that is then dereferenced by a %s log conversion. The lookup is reached only from a debug log statement (NET_DBG / LOG_DBG), so the out-of-bounds read is triggerable only when the DHCPv4 log module is built at DEBUG level (CONFIG_NET_DHCPV4_LOG_LEVEL_DBG), which is not the default configuration. When that condition holds, the result is an out-of-bounds read and a wild-pointer dereference: most likely a crash of the DHCP client (denial of service) and potentially disclosure of an adjacent pointer's contents through the log output. The fix replaces sizeof with ARRAY_SIZE, restoring the correct 1..8 acceptance window.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-10773 since 06/03/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 4.5.0 eliminates this vulnerability. Applying the patch 73c8a7df4f00088fc04ee5ab71bcabf47fcd3db7 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• ZephyrProject

Name

• Zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

CPE 2.3info

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CPE 2.2info

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