dhcpcd Heap Use-After-Free via Control Socket Handling

published 2026-06-23 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-38498

cvss: 4.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits: 0; none known

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.

Patch / fix

distros 5 links 1

debian suse opensuse alpine azure linux

dhcpcd Debian 13 1:10.1.0-11+deb13u3
dhcpcd Debian 14 1:10.3.2-4

debian advisories DEBIAN-CVE-2026-56117

dhcpcd SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 10.5.0-160000.1.1

suse advisories SUSE-SU-2026:23400-1 SUSE-SU-2026:23562-1

dhcpcd openSUSE Leap 16.0 10.5.0-160000.1.1
dhcpcd openSUSE Tumbleweed 10.5.0-1.1

opensuse advisories openSUSE-SU-2026:21692-1 openSUSE-SU-2026:11473-1

dhcpcd Alpine 3.24, Alpine 3.23 10.5.2-r0

alpine advisories ALPINE-CVE-2026-56117

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

dhcpcd Azure Linux 3.0 10.0.8-2

azure linux advisories AZL-90222

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

github.com/NetworkConfiguration/dhcpcd@78ea09e commit

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-56117 updated 2026-11-05 cvss 4.7

dhcpcd: dhcpcd: Local heap use-after-free vulnerability leads to denial of service.

Red Hat Enterprise Linux 10 dhcpcd
affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 4 mo ago (2026-06-24)

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.7	CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA	3.1	4.7	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA	4.0	5.7	CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

NetworkConfiguration dhcpcd

Classification

Weakness

CWE-416 Use After Free

References

Sources

CVE List CVE-2026-56117
NVD CVE-2026-56117

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary