What’s Vulnerable › Vulnerabilities

CVE-2026-56114: dhcpcd Stack Out-of-Bounds Write in dhcp6_makemessage()

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-23 · updated 2026-10-25
• Weakness: CWE-787

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.

Affected products

• NetworkConfiguration dhcpcd: through 10.3.2

References

• https://github.com/NetworkConfiguration/dhcpcd/commit/2f00c7bfc408b6582d331932dfa47829c4819029
• https://www.vulncheck.com/advisories/dhcpcd-stack-out-of-bounds-write-in-dhcp6-makemessage

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