CVE-2026-56113 dhcpcd Heap Use-After-Free in dhcp6_deprecateaddrs via DHCPv6 RENEW

Medium 6.0 Published 23 Jun 2026 Updated 28 Jul 2026

Unauthenticated attackers can crash the dhcpcd daemon by sending crafted DHCPv6 RENEW replies, causing a heap use-after-free.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-56113?

CVE-2026-56113 is a medium-severity use after free vulnerability in NetworkConfiguration dhcpcd, published on 23 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

dhcpcd through 10.3.2, fixed in commit 5733d3c, contains a heap use-after-free vulnerability that allows unauthenticated same-link attackers to crash the daemon by sending a crafted DHCPv6 RENEW reply with RFC6603 OPTION_PD_EXCLUDE and both preferred and valid lifetimes set to zero. Attackers acting as or impersonating a DHCPv6 server can trigger dhcp6_deprecatedele() to free a delegated child address while an outer TAILQ_FOREACH_SAFE iterator in dhcp6_deprecateaddrs() still holds the freed pointer, causing a use-after-free when TAILQ_REMOVE is reached.

Weakness: CWE-416

Which versions are affected by CVE-2026-56113?

It affects 1 product.

Products include Dhcpcd Project Dhcpcd.

How do I fix CVE-2026-56113?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-56113 being exploited?

There is no known exploitation of CVE-2026-56113 in the wild and no public exploit code.

Sources

Also known as ALPINE-CVE-2026-56113, AZL-90213, BELL-CVE-2026-56113, DEBIAN-CVE-2026-56113, GHSA-vh4p-87xg-jc4x, UBUNTU-CVE-2026-56113.