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Advisory severityMedium6.5Red Hat Linux

Medium [CVE-2026-56116] Denial of Service via IPv6 Router Advertisement memory leak

This medium-severity Red Hat Linux advisory covers CVE-2026-56116 affecting Red Hat Enterprise Linux 10, Red Hat package: dhcpcd.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-56116 Source published Source updated

VulniPulse record published Record updated

CVE-2026-56116
Affected products & platforms
Red Hat LinuxRed Hat Enterprise Linux
Open source advisory

Summary

dhcpcd through 10.3.2, fixed in commit 708b4a5, contains a memory leak vulnerability in the IPv6 Router Advertisement route information handling that allows an unauthenticated same-link attacker to cause denial of service by sending crafted Router Advertisements.

Attackers can repeatedly send Router Advertisements containing Route Information options with a lifetime of zero, triggering unfreed allocations in routeinfo_findalloc() that cause linear memory exhaustion and eventual daemon crash. A flaw was found in dhcpcd.

By repeatedly sending specially crafted Router Advertisements with a zero lifetime, the attacker can cause the system to exhaust its memory, leading to a denial of service and a daemon crash. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-772. 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-2026-56116 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-56116 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-2026-56116?

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

Fixed versions
  • 10.3.2

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • To mitigate this issue, consider disabling IPv6 on systems where it is not required. This can be achieved temporarily by running `sudo sysctl -w net.ipv6.conf.all.disable_ipv6=1` and `sudo sysctl -w net.ipv6.conf.default.disable_ipv6=1`. For permanent disablement, add `net.ipv6.conf.all.disable_ipv6 = 1` and `net.ipv6.conf.default.disable_ipv6 = 1` to a file like `/etc/sysctl.d/99-disable-ipv6.conf` and apply with `sudo sysctl -p`. Disabling IPv6 may impact network functionality that relies on it. A system restart or network service reload may be required for changes to take effect.

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

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