CVE-2026-15816 in Red Hat
Summary
by MITRE • 08/07/2026
A flaw was found in dracut. The die() error-handling function writes its message into a shell script under the initramfs emergency-hook directory without properly shell-quoting it. When the message contains data derived from the DHCP ROOT_PATH option, an attacker on the adjacent network who controls a rogue DHCP server can inject a command-substitution sequence that executes as root the next time dracut sources its emergency hook scripts during standard boot-failure handling.
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Analysis
by VulDB Data Team • 08/07/2026
This vulnerability resides within the dracut initramfs framework where the die() error-handling function fails to properly shell-quote diagnostic messages before writing them to shell scripts in the emergency-hook directory. The flaw creates a command injection vector when DHCP ROOT_PATH option data is processed and written directly into script files without adequate sanitization. This represents a critical security weakness that violates standard input validation practices and exposes systems to remote code execution risks.
The technical exploitation occurs through an adjacent network attacker who controls a rogue DHCP server capable of manipulating the ROOT_PATH option returned during DHCP negotiations. When vulnerable systems process this malicious data, the unescaped content gets written into shell scripts within the initramfs environment under the emergency-hook directory structure. The subsequent boot failure handling mechanism executes these compromised scripts with root privileges, enabling arbitrary command execution as the privileged user.
This vulnerability directly maps to CWE-78 and CWE-20 categories, representing shell injection flaws and improper input sanitization respectively. The attack vector aligns with ATT&CK technique T1059.004 for command and scripting interpreter usage, specifically leveraging shell script execution during system recovery phases. The impact spans from local privilege escalation to complete system compromise, as the injected commands execute with root privileges during emergency boot handling scenarios.
The operational impact extends beyond immediate system compromise to include potential denial of service conditions where legitimate boot processes fail due to malicious script injection. Organizations relying on automated boot processes or network-based recovery mechanisms face heightened risk exposure. The vulnerability affects systems that utilize dracut for initramfs generation and depend on DHCP for network configuration during early boot stages, particularly prevalent in enterprise environments with centralized network management.
Mitigation strategies include immediate patching of affected dracut versions, implementing network segmentation to limit DHCP server access, and deploying DHCP snooping mechanisms to prevent rogue DHCP server operations. Administrators should also consider disabling unnecessary emergency hook functionality where possible and regularly auditing initramfs contents for unauthorized modifications. Network monitoring solutions should be configured to detect anomalous DHCP responses containing suspicious command injection patterns that could indicate exploitation attempts against this vulnerability.