Persistent RCP hang via traffic-triggered race condition
Published Jul 30, 2025 · Updated Jul 30, 2025
Improper locking in Silicon Labs Zigbee EmberZNet allows remote authenticated users to hang an RCP through heavy adjacent traffic. In a 15.4+BLE RCP, heavy network traffic triggers a race condition that prevents the radio co-processor from sending messages to CPCd. The attacker requires low-privileged adjacent-network access, and the communication failure persists until the device undergoes a hard reset.
Summary
What happened
Improper locking in Silicon Labs Zigbee EmberZNet allows remote authenticated users to hang an RCP through heavy adjacent traffic. In a 15.4+BLE RCP, heavy network traffic triggers a race condition that prevents the radio co-processor from sending messages to CPCd. The attacker requires low-privileged adjacent-network access, and the communication failure persists until the device undergoes a hard reset.
The record
- CVE
- CVE-2025-1221
- Published
- Jul 30, 2025
- Updated
- Jul 30, 2025
- Vendor
- Sigma Designs
- Product
- Zigbee EmberZNet
- Classifications
- CWE-667, CAPEC-26, T1499
- Attack vector
- adjacent
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 30, 2025CVE publishedPublication date reported by the CVE source.
- Jul 30, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <=2024.6.1
- Affected versionversion=0 <=4.3.3
- Affected versionversion=4.4.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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