The eswifi socket offload driver copies user-provided payloads into a fixed buffer without checking available space; oversized sends overflow `eswifi-...
Description
The eswifi socket offload driver copies user-provided payloads into a fixed buffer without checking available space; oversized sends overflow `eswifi->buf`, corrupting kernel memory (CWE-120)
Remediation
Apply vendor security updates immediately. Monitor for exploitation attempts and review access logs.
---METADATA---
VENDOR: Zephyr Project
PRODUCT: Zephyr RTOS
AFFECTED_VERSIONS: See vendor advisory
---END_METADATA---
Description Summary:
A buffer management flaw in dns_unpack_name() allows unauthenticated attackers to trigger an out-of-bounds write via malicious DNS responses when CONFIG_DNS_RESOLVER is enabled.
Executive Summary:
A critical out-of-bounds write vulnerability in the Zephyr RTOS DNS resolver could allow unauthenticated attackers to compromise affected IoT devices via malicious DNS traffic.
Vulnerability Details
CVE-ID: CVE-2026-1678
Affected Software: Zephyr RTOS (DNS Resolver Component)
Affected Versions: See vendor advisory for specific affected versions
Vulnerability: The
dns_unpack_name()function incorrectly caches buffer tailroom while appending DNS labels. This leads to an incorrect size calculation as the buffer grows, allowing a final null terminator to be written past the buffer boundaries. An unauthenticated remote attacker can exploit this by sending a malicious DNS response to a device withCONFIG_DNS_RESOLVERenabled.Business Impact
With a CVSS score of 9.4, this vulnerability poses a severe risk to embedded and IoT systems. Successful exploitation can lead to memory corruption, system crashes, or potentially remote code execution (RCE). In industrial or medical contexts, such a compromise could result in significant operational disruption or safety risks, as the attacker gains control over low-level system memory.
Remediation Plan
Immediate Action: Update the Zephyr RTOS kernel to the latest version that includes the fix for the DNS unpacking logic.
Proactive Monitoring: Monitor for unusual DNS traffic patterns or frequent crashes of embedded devices that utilize the Zephyr DNS resolver.
Compensating Controls: Use a secure DNS proxy or firewall to inspect and sanitize DNS responses before they reach the affected IoT devices.
Exploitation Status
Public Exploit Available: false
Analyst Notes: As of March 5, 2026, there is no public information indicating active exploitation of this vulnerability. However, memory corruption flaws in common RTOS components are frequently targeted once details become public.
Analyst Recommendation
Organizations deploying devices based on Zephyr RTOS must verify if
CONFIG_DNS_RESOLVERis active and apply the necessary kernel updates immediately. Because this vulnerability is triggered by incoming network traffic (DNS responses), it is highly reachable and requires urgent remediation to protect the device fleet.