Use After Free in Dhcpcd Project
CVE-2026-56113
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.
Vulnerability class: Use-After-Free
EPSS: 0.003 (19.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Dhcpcd_project Dhcpcd
- Networkconfiguration Dhcpcd — versions 0, 5733d3c59a5651f64357ac11c98b4f39895c8d25
Weakness classification (CWE)
References
- disclosure@vulncheck.com (Patch, patch)
- disclosure@vulncheck.com (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-56113?
- CVE-2026-56113 is a medium-severity vulnerability in Dhcpcd Project, classified under Use After Free. CVSS score: 5.3/10. Published 2026-06-23.
- How severe is CVE-2026-56113?
- Medium severity. CVSS v3 base score is 5.3 out of 10.