CVE-2026-79980 zephyrproject CVE debrief

Who should care

Network administrators and security teams should assess exposure and prioritize remediation for devices using the affected DHCPv4 client implementation. This vulnerability can potentially allow attackers to redirect network traffic or cause other security issues.

Why it matters

The CVE-2026-79980 vulnerability involves a predictable transaction identifier in the DHCPv4 client implementation, allowing for potential network traffic redirection and other security issues. Network administrators and security teams should assess exposure and prioritize remediation for devices using the affected implementation.

• Potential network traffic redirection
• Reconfiguration of device network settings
• Possible exploitation by attackers to gain control of device traffic

Technical summary

The DHCPv4 client implementation uses a predictable transaction identifier, which is a counter rather than a random value. This allows an attacker to forge replies that can reconfigure the device's network settings, potentially redirecting traffic or causing other security issues. The issue arises from the client's use of a counter rather than a random value for the transaction identifier, which is not in line with RFC 2131 requirements. An attacker who learns one identifier can retain a valid token for the device's whole uptime and predict later identifiers without observing unicast renew traffic. The fix draws a fresh sys_rand32_get() value at each point where a transaction begins — entering SELECTING, RENEW,

Defensive priority

Medium

Recommended defensive actions

• Review and update DHCPv4 client configurations to ensure randomness of transaction identifiers
• Implement additional network monitoring to detect potential forged replies
• Verify device configurations and update to the latest version if available
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability. The Zephyr Project has also provided source references on GitHub. However, the corpus does not establish versions, exploitation, impact, or remediation, which require verification from the supplied official sources.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.