Medium [CVE-2026-56117] Local heap use-after-free vulnerability leads to denial of service.
This medium-severity Red Hat Linux advisory covers CVE-2026-56117 affecting Red Hat Enterprise Linux 10, Red Hat package: dhcpcd.
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Summary
dhcpcd through 10.3.2, fixed in commit 78ea09e, contains a heap use-after-free vulnerability in the control socket handling within src/control.c that allows local unprivileged attackers to trigger memory corruption when privilege separation is disabled.
Attackers can connect to the control socket and send a privileged command such as -x, causing control_recvdata() to free the client object while the same READ+HANGUP event subsequently reaches control_hangup() with the stale pointer, resulting in a use-after-free condition exploitable in deployments using --disable-privsep or where privsep initialization has failed with the control socket operating in mode 0666.
A flaw was found in dhcpcd. This occurs when privilege separation is disabled, enabling the attacker to send a privileged command to the control socket.
Successful exploitation can lead to a denial of service. Red Hat severity: Moderate — CVSS 4.7 (CVSS:3.1/AV:L/AC:H/PR:L/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.
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 checklist
- Ensure that the `dhcpcd` service is configured to run with privilege separation enabled. If `dhcpcd` is running with privilege separation disabled (e.g., via `--disable-privsep`), re-enable it to prevent local unprivileged attackers from exploiting this vulnerability. If privilege separation cannot be enabled, restrict access to the system running `dhcpcd` or disable the `dhcpcd` service if it is not critical for network operations. If the `dhcpcd` service is reconfigured, a restart may be required for changes to take effect.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
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