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Fencer Vulns
high 7.5

CVE-2023-28840 json

moby/moby's dockerd daemon encrypted overlay network may be unauthenticated

published 2023-04-04 3 y ago modified 2026-09-10 59 d ago also EUVD-2023-1150 , GHSA-232p-vwff-86mp , GO-2023-1699

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.6%
EPSS 2.6% chance of exploitation in 30 days, percentile 85%
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 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.

Two iptables rules serve to filter incoming VXLAN datagrams with a VNI that corresponds to an encrypted network and discards unencrypted datagrams. The rules are appended to the end of the INPUT filter chain, following any rules that have been previously set by the system administrator. Administrator-set rules take precedence over the rules Moby sets to discard unencrypted VXLAN datagrams, which can potentially admit unencrypted datagrams that should have been discarded.

The injection of arbitrary Ethernet frames can enable a Denial of Service attack. A sophisticated attacker may be able to establish a UDP or TCP connection by way of the container’s outbound gateway that would otherwise be blocked by a stateful firewall, or carry out other escalations beyond simple injection by smuggling packets into the overlay network.

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. Close the VXLAN port (by default, UDP port 4789) to incoming traffic at the Internet boundary to prevent all VXLAN packet injection, and/or ensure that the `xt_u32` kernel module is available on all nodes of the Swarm cluster.

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-2023-28840

  • 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

ubuntu advisories UBUNTU-CVE-2023-28840

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-compose openSUSE Tumbleweed 2.17.3-1.1
  • kubescape openSUSE Tumbleweed 2.3.6-1.1
  • docker openSUSE Tumbleweed 24.0.5_ce-2.1

opensuse advisories openSUSE-SU-2025:15589-1openSUSE-SU-2024:12876-1openSUSE-SU-2024:13005-1openSUSE-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-2023-28840

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-2023-28840 updated cvss 8.7

moby: Encrypted overlay network may be 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 Logging Subsystem for Red Hat OpenShift openshift-logging/cluster-logging-rhel8-operator Red Hat OpenShift Service Mesh 2 openshift-service-mesh/pilot-rhel8, openshift-service-mesh/proxyv2-rhel8, openshift-service-mesh/istio-cni-rhel8, openshift-service-mesh/istio-rhel8-operator 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, +11 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
    +1 more products
    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

2.56% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/moby/moby/issues/43382 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:L
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:L
NVD 3.1 8.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:H

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-203 Observable Discrepancy
  • 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.