CVE-2026-14373: HashiCorp Nomad Privilege Escalation Flaw

CVE-2026-14373 Overview

CVE-2026-14373 affects HashiCorp Nomad and Nomad Enterprise on Linux clients running the Docker task driver. The Nomad Docker driver fails to enforce the allow_privileged restriction when jobs request host namespace mode options. An authenticated job submitter can run a container inside a host namespace and access information belonging to the host or to other workloads sharing the same client node. The flaw is tracked as a missing authorization issue [CWE-862] and carries a CVSS score of 7.7. HashiCorp addressed the issue in Nomad Community Edition 2.0.4 and Nomad Enterprise 2.0.4, 1.11.8, and 1.10.14.

Critical Impact
An authenticated Nomad user with job submission rights can bypass privileged-container restrictions to break workload isolation and access host or co-tenant data.

Affected Products

HashiCorp Nomad Community Edition prior to 2.0.4
HashiCorp Nomad Enterprise prior to 2.0.4, 1.11.8, and 1.10.14
Nomad Linux clients configured with the Docker task driver

Discovery Timeline

2026-07-08 - CVE-2026-14373 published to NVD
2026-07-08 - Last updated in NVD database

Technical Details for CVE-2026-14373

Vulnerability Analysis

Nomad's Docker task driver exposes several configuration options that map container namespaces onto the host. These include network_mode = "host", pid_mode = "host", ipc_mode = "host", and userns_mode = "host". Operators normally restrict these options by disabling allow_privileged in the driver plugin configuration. In vulnerable releases the driver does not consult that setting when processing host namespace mode options. Any authenticated user permitted to submit jobs to a namespace can therefore request a container that runs in the host network, PID, IPC, or user namespace regardless of operator policy. Once inside the host namespace, the workload can enumerate processes, sniff traffic on host interfaces, and reach IPC endpoints belonging to other tenants on the same client.

Root Cause

The root cause is a missing authorization check [CWE-862] in the Docker task driver's configuration validation path. The allow_privileged gate is applied to Docker's --privileged flag and closely related options but not to the host namespace mode fields. Job specifications flow into the Docker Engine with the requested namespace bindings intact.

Attack Vector

Exploitation requires a valid Nomad ACL token with permission to submit jobs to at least one namespace on a client running the Docker driver. The attacker crafts a job specification that sets one or more host namespace mode options in the task's config block. When the client schedules the task, Docker attaches the container to the requested host namespace. From that position the attacker reads host-level information or interferes with neighboring workloads on the same node. No user interaction is required and the attack traverses the Nomad API over the network.

The vulnerability is described in detail in the HashiCorp Security Advisory HCSEC-2026-19.

Detection Methods for CVE-2026-14373

Indicators of Compromise

Job specifications submitted through the Nomad API containing network_mode, pid_mode, ipc_mode, or userns_mode set to host on clients where allow_privileged is disabled.
Docker containers on Nomad client nodes running with HostConfig.NetworkMode, PidMode, or IpcMode equal to host that are not associated with system jobs.
Unexpected process enumeration, packet capture, or access to /proc entries of other workloads originating from Nomad-managed containers.

Detection Strategies

Audit the Nomad /v1/jobs and /v1/job/{id} API endpoints for submissions that include host namespace mode options and correlate with the submitting ACL identity.
Inspect Docker daemon logs and docker inspect output on client nodes to flag containers bound to host namespaces launched by non-privileged Nomad job owners.
Compare running task configurations against approved job specifications stored in version control to identify drift introduced through unauthorized privileged options.

Monitoring Recommendations

Forward Nomad audit logs and Docker Engine events to a central analytics platform and alert on host namespace usage tied to specific submitter tokens.
Track ACL token activity, especially newly issued tokens with submit-job capability against namespaces that host multi-tenant workloads.
Baseline expected container namespace configurations per client node and alert on deviations.

How to Mitigate CVE-2026-14373

Immediate Actions Required

Upgrade Nomad Community Edition to 2.0.4 and Nomad Enterprise to 2.0.4, 1.11.8, or 1.10.14 depending on the deployed branch.
Review outstanding job specifications and terminate any tasks currently using host namespace mode options that were not sanctioned by operators.
Rotate Nomad ACL tokens held by untrusted job submitters and tighten namespace-scoped policies.

Patch Information

HashiCorp released fixed versions on the branches noted in HCSEC-2026-19. The patched Docker task driver enforces allow_privileged on host namespace mode options in addition to the previously guarded settings. Upgrade the Nomad server and client binaries on all Linux nodes running the Docker driver.

Workarounds

Restrict submit-job ACL capability to trusted operators until all clients are patched.
Isolate multi-tenant workloads onto separate client node pools so that host namespace access cannot reach other customers' data.
Use Nomad namespace and node pool constraints to prevent untrusted jobs from scheduling on Docker-enabled clients.

bash

# Verify Nomad versions on server and client nodes
nomad version

# List running Docker containers using host namespaces on a client node
docker ps --quiet | xargs -r docker inspect \
  --format '{{.Name}} net={{.HostConfig.NetworkMode}} pid={{.HostConfig.PidMode}} ipc={{.HostConfig.IpcMode}} userns={{.HostConfig.UsernsMode}}' \
  | grep -E 'net=host|pid=host|ipc=host|userns=host'