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Fencer Vulns
medium 6.8

CVE-2023-28842 json

moby/moby's dockerd daemon encrypted overlay network with a single endpoint is unauthenticated

published 2023-04-04 3 y ago modified 2026-09-10 59 d ago also EUVD-2023-1220 , GHSA-6wrf-mxfj-pf5p , GO-2023-1701

cvss
6.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 73%
public exploits
0
none known

Summary

Moby) is an open source container framework developed by Docker Inc. that is distributed as Docker, Mirantis Container Runtime, and various other downstream projects/products. The Moby daemon component (`dockerd`), which is developed as moby/moby is commonly referred to as *Docker*.

Swarm Mode, which is compiled in and delivered by default in `dockerd` and is thus present in most major Moby downstreams, is a simple, built-in container orchestrator that is implemented through a combination of SwarmKit and supporting network code.

The `overlay` network driver is a core feature of Swarm Mode, providing isolated virtual LANs that allow communication between containers and services across the cluster. This driver is an implementation/user of VXLAN, which encapsulates link-layer (Ethernet) frames in UDP datagrams that tag the frame with the VXLAN metadata, including a VXLAN Network ID (VNI) that identifies the originating overlay network. In addition, the overlay network driver supports an optional, off-by-default encrypted mode, which is especially useful when VXLAN packets traverses an untrusted network between nodes.

Encrypted overlay networks function by encapsulating the VXLAN datagrams through the use of the IPsec Encapsulating Security Payload protocol in Transport mode. By deploying IPSec encapsulation, encrypted overlay networks gain the additional properties of source authentication through cryptographic proof, data integrity through check-summing, and confidentiality through encryption.

When setting an endpoint up on an encrypted overlay network, Moby installs three iptables (Linux kernel firewall) rules that enforce both incoming and outgoing IPSec. These rules rely on the `u32` iptables extension provided by the `xt_u32` kernel module to directly filter on a VXLAN packet's VNI field, so that IPSec guarantees can be enforced on encrypted overlay networks without interfering with other overlay networks or other users of VXLAN.

The `overlay` driver dynamically and lazily defines the kernel configuration for the VXLAN network on each node as containers are attached and detached. Routes and encryption parameters are only defined for destination nodes that participate in the network. The iptables rules that prevent encrypted overlay networks from accepting unencrypted packets are not created until a peer is available with which to communicate.

Encrypted overlay networks silently accept cleartext VXLAN datagrams that are tagged with the VNI of an encrypted overlay network. As a result, it is possible to inject arbitrary Ethernet frames into the encrypted overlay network by encapsulating them in VXLAN datagrams. The implications of this can be quite dire, and GHSA-vwm3-crmr-xfxw should be referenced for a deeper exploration.

Patches are available in Moby releases 23.0.3, and 20.10.24. As Mirantis Container Runtime's 20.10 releases are numbered differently, users of that platform should update to 20.10.16.

Some workarounds are available. In multi-node clusters, deploy a global ‘pause’ container for each encrypted overlay network, on every node. For a single-node cluster, do not use overlay networks of any sort. Bridge networks provide the same connectivity on a single node and have no multi-node features. The Swarm ingress feature is implemented using an overlay network, but can be disabled by publishing ports in `host` mode instead of `ingress` mode (allowing the use of an external load balancer), and removing the `ingress` network. If encrypted overlay networks are in exclusive use, block UDP port 4789 from traffic that has not been validated by IPSec.

Patch / fix

  • go github.com/docker/docker 20.10.24, 20.10.24+incompatible, 23.0.3, 23.0.3+incompatible
  • mobyproject moby 20.10.24, 23.0.3
  • docker.io Debian 14, Debian 13, Debian 12 20.10.24+dfsg1-1

debian advisories DEBIAN-CVE-2023-28842

  • docker.io-app Ubuntu 22.04 LTS 27.5.1-0ubuntu3~22.04.2
  • docker.io Ubuntu Pro 18.04 LTS 20.10.21-0ubuntu1~18.04.3+esm3
  • docker.io Ubuntu Pro 20.04 LTS 20.10.21-0ubuntu1~20.04.6+esm2
  • docker.io Ubuntu Pro 22.04 LTS 20.10.21-0ubuntu1~22.04.7+esm2
  • docker.io-app Ubuntu Pro 20.04 LTS 26.1.3-0ubuntu1~20.04.1+esm1

ubuntu advisories UBUNTU-CVE-2023-28842

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • docker-stable SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +12 more 24.0.9_ce-150000.1.25.1
  • docker SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES for SAP 15 SP1 +16 more 24.0.5_ce-150000.185.1
  • docker SLE Module for Containers 12 20.10.25_ce-98.93.1
  • docker-stable SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 24.0.9_ce-1.20.1

suse advisories SUSE-SU-2025:03545-1SUSE-SU-2025:03540-1SUSE-SU-2023:3536-1SUSE-SU-2023:3307-1

  • docker-stable openSUSE Tumbleweed 24.0.9_ce-15.1
  • docker openSUSE Tumbleweed 24.0.5_ce-2.1

opensuse advisories openSUSE-SU-2025:15589-1openSUSE-SU-2024:13205-1

  • docker Alpine 3.17 20.10.24-r0
  • docker Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 23.0.3-r0

alpine advisories ALPINE-CVE-2023-28842

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

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-2023-28842 updated cvss 6.8

moby: Encrypted overlay network with a single endpoint is unauthenticated

  • Red Hat multicluster engine for Kubernetes 2.4 for RHEL 8 multicluster-engine/hive-rhel8 v2.4.4-8, multicluster-engine/work-rhel8 v2.4.4-6, multicluster-engine/discovery-rhel8 v2.4.4-8, multicluster-engine/placement-rhel8 v2.4.4-6, multicluster-engine/cluster-api-rhel8 v2.4.4-7, multicluster-engine/console-mce-rhel8 v2.4.4-9, +36 more
    fixed: vendor fix RHBA-2024:1246
  • Red Hat OpenShift Service Mesh 2 openshift-service-mesh/pilot-rhel8, openshift-service-mesh/proxyv2-rhel8 Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/agent-service-rhel8, rhacm2/assisted-installer-rhel8, rhacm-assisted-service-container, rhacm2/assisted-installer-agent-rhel8, rhacm2/assisted-installer-reporter-rhel8, rhacm2/multicluster-operators-subscription-rhel8, +1 more Red Hat Advanced Cluster Security 3 advanced-cluster-security/rhacs-scanner-rhel8, advanced-cluster-security/rhacs-scanner-db-rhel8, advanced-cluster-security/rhacs-scanner-slim-rhel8, advanced-cluster-security/rhacs-scanner-db-slim-rhel8 Red Hat OpenShift Container Platform 4 openshift4/ose-console, openshift4/ose-installer, openshift4/ose-ptp-operator, openshift4/ptp-must-gather-rhel8, openshift4/ovirt-csi-driver-rhel8, openshift4/ose-installer-artifacts, +10 more Red Hat OpenShift Container Platform Assisted Installer 1 rhai-tech-preview/assisted-installer-rhel8, rhai-tech-preview/assisted-installer-agent-rhel8, rhai-tech-preview/assisted-installer-reporter-rhel8 Red Hat Quay 3 clair-jwt-container
    not affected: vulnerable code not present

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
20 mo ago

Exploit prediction

1.44% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
GitHub 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
NVD 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/docker/docker
>=1.12.0, <20.10.24
>=23.0.0, <23.0.3
>=1.12.0, <20.10.24+incompatible
>=23.0.0+incompatible, <23.0.3+incompatible
20.10.24
23.0.3
20.10.24+incompatible
23.0.3+incompatible

Affected products

  • moby moby

Classification

Weakness
  • CWE-420 Unprotected Alternate Channel
  • CWE-636 Not Failing Securely
  • CWE-755 Improper Handling of Exceptional Conditions
Technology feeds

References

Sources

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.

The maintainers of moby/moby published their own advisory on GitHub. Reviewed sources take precedence over it.