CVE-2026-56116
Description
A flaw was found in dhcpcd. An unauthenticated attacker on the same network link can exploit a memory leak vulnerability in the IPv6 Router Advertisement route information handling. 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.
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Adjacent Network | N/A | Adjacent Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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