Medium [CVE-2026-56113] Denial of Service via crafted DHCPv6 RENEW reply
This medium-severity Red Hat Linux advisory covers CVE-2026-56113 affecting Red Hat Enterprise Linux 10, Red Hat package: dhcpcd.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
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. A flaw was found in dhcpcd.
This can lead to a Denial of Service (DoS), causing the dhcpcd daemon to crash due to a heap use-after-free vulnerability. Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-825. Affected Red Hat products: Red Hat Enterprise Linux 10.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: dhcpcd.
Is CVE-2026-56113 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-56113 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-56113?
Upgrade to a fixed release named by Red Hat:
- 10.3.2
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
Mitigation
Upgrade to a fixed release: 10.3.2. That is the remediation for this advisory.
The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
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