CVE-2026-56114

Medium

Description

dhcpcd through 10.3.2, fixed in commit 2f00c7b, contains a one-byte stack out-of-bounds write vulnerability in dhcp6_makemessage() in src/dhcp6.c that allows unauthenticated same-link attackers to write beyond a fixed local buffer by serializing an oversized RFC6603 OPTION_PD_EXCLUDE option body. Attackers can send a crafted DHCPv6 ADVERTISE message containing an IA_PD IAPREFIX /0 with a valid OPTION_PD_EXCLUDE using an exclude prefix length of /121 through /128 to trigger the out-of-bounds write and potentially corrupt adjacent stack memory.

SeverityMedium

CVSS5.3

Exploit probability19. percentile0.3%

ProductDhcpcd

PublishedJun 23, 2026

First seenJun 23, 2026

Weakness typeCWE-787Out-of-bounds write

How to fix

Patches

github.com/NetworkConfiguration/dhcpcd/commit/2f00c7bfc408b6582d331932dfa47829c4819029

Affected products

Product	Affected versions	Fixed in
dhcpcd_project dhcpcd	v ≤ 10.3.2	—

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