CVE-2026-47145: EmberZNet DoS Vulnerability via Color Control Messages

Technical summary

CVE-2026-47145 is a denial-of-service vulnerability in Silicon Labs' EmberZNet protocol stack stemming from improper input validation of Color Control cluster messages. The flaw triggers assertion failures that terminate the process when malformed messages are received. The vulnerability is classified under CWE-617 (Reachable Assertion), indicating that an attacker-controlled code path leads to an unhandled assertion. Exploitation mandates prior network membership, as the Color Control messages must originate from an already-authenticated device on the ZigBee network. The CVSS 3.1 score of 6.5 (MEDIUM) reflects high availability impact with low attack complexity and a requirement for local network privileges.

Business impact

This vulnerability creates operational risk for organizations deploying EmberZNet-based IoT and smart home devices. An attacker with network access (insider threat or compromised peer device) can cause unscheduled service interruptions by crashing Color Control-enabled devices. In critical environments—healthcare facilities, industrial automation, building management systems—unexpected device shutdowns can disrupt workflows, trigger manual interventions, and degrade system reliability. The financial impact depends on deployment scale and uptime requirements, but should not be underestimated in multi-device ecosystems where cascade effects are possible.

Affected systems

Silicon Labs EmberZNet versions 9.0.2 and earlier are affected. EmberZNet is the company's proprietary ZigBee protocol stack used in wireless mesh networking products. Any endpoint or gateway device running a vulnerable EmberZNet version and supporting the Color Control cluster is at risk. Organizations should audit their IoT device firmware versions and cluster configurations to identify exposure. Devices that do not use the Color Control cluster are not vulnerable to this specific flaw.

Exploitability

Exploitation requires the attacker to be an authenticated member of the ZigBee network and to send crafted Color Control messages. This is not a remote, unauthenticated attack over the public internet. The attack complexity is low once network access is established, and no user interaction is required. The barrier to exploitation is the network boundary—an insider or an attacker who has compromised a trusted peer device can initiate the attack. The vulnerability is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog, suggesting limited public weaponization to date, but the simplicity of crafting malformed messages means the risk could increase as awareness spreads.

Remediation

Upgrade EmberZNet to a patched version released by Silicon Labs. Verify the specific version number against the vendor's security advisory. Until patching is complete, network segmentation and access controls can reduce exposure—restrict which devices are permitted to join the network and monitor for unusual Color Control message patterns. Disable the Color Control cluster on devices where it is not functionally required.

Patch guidance

Contact Silicon Labs or consult their official security advisories to identify the minimum patched version for EmberZNet. Apply firmware updates to all affected devices in your deployment. Prioritize endpoints that support the Color Control cluster and are exposed to untrusted internal network traffic. Test patches in a non-production environment first to ensure compatibility with dependent applications and integrations. Establish a rolling update schedule if simultaneous patching is not feasible.

Detection guidance

Monitor device logs for unexpected process terminations, crashes, or restarts coinciding with Color Control cluster activity. Network-level detection is challenging without specialized ZigBee packet inspection, but alerting on abnormal cluster message patterns or repeated device disconnections may reveal exploitation attempts. Implement device health checks that alert when Color Control-enabled endpoints go offline unscheduled. Track firmware versions across your device inventory to ensure patched versions are consistently deployed.

Why prioritize this

This vulnerability merits prompt but not emergency-level response. The MEDIUM severity score reflects the combination of high availability impact and a significant barrier to exploitation (network membership requirement). Organizations with large deployments of Color Control devices, particularly in uptime-sensitive environments, should prioritize patching. Those with strong network access controls and device authentication practices face lower immediate risk but should still treat it as a near-term remediation task.

Risk score, explained

The CVSS 3.1 score of 6.5 balances high impact on availability (A:H) against low attack complexity (AC:L) and a requirement for authenticated network access (PR:L). The vector indicates no confidentiality or integrity impact, confirming this is purely a denial-of-service issue. The score reflects realistic threat scenarios in an internal network context; an insider or compromised peer device can reliably crash vulnerable endpoints with minimal effort.

Frequently asked questions