Stack Out-of-Bounds Write Vulnerability in dhcpcd by Network Configuration

CVE-2026-56114

What is CVE-2026-56114?

The dhcpcd product prior to version 10.3.2 is susceptible to a stack out-of-bounds write vulnerability in the dhcp6_makemessage() function located in src/dhcp6.c. This flaw enables unauthenticated attackers on the same network link to exploit an oversized RFC6603 OPTION_PD_EXCLUDE option body, resulting in potential overwrites of adjacent stack memory. By sending a specifically crafted DHCPv6 ADVERTISE message that includes an IA_PD IAPREFIX /0 with a legitimate OPTION_PD_EXCLUDE of prefix lengths between /121 and /128, an attacker can trigger this vulnerability, leading to unpredictable behavior or system compromise.

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