CVE-2026-10773
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.
Does this matter?
Lower severity and a low EPSS score (0.28%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.4 MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
- EPSS
- 0.28% probability · 21th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-125, CWE-682
- Affected
- zephyrproject/zephyr
- Source
- vulnerabilities@zephyrproject.org
References
- https://github.com/zephyrproject-rtos/zephyr/commit/73c8a7df4f00088fc04ee5ab71bcabf47fcd3db7Patch
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r5hq-xq42-wcfqExploit, Patch, Vendor Advisory
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r5hq-xq42-wcfqExploit, Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.