CVE-2026-15816
Description
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.
Statement
Red Hat Product Security rates this flaw's impact as Important. Exploitation requires an attacker-controlled or spoofed DHCP server on the same network segment as a system performing network boot (root=dhcp/netroot=dhcp), and for the DHCP-supplied ROOT_PATH value to fail dracut's netroot handler resolution -- both fully within an adjacent-network attacker's control. Reaching the point where the poisoned hook script is actually sourced depends on dracut's boot-failure handling reinvoking the emergency shell mechanism, which occurs by default when the netroot handler cannot be resolved. This is a separate code path from CVE-2026-6893, which patched modules.d/35network-legacy/dhclient-script.sh but did not modify dracut-lib.sh's die() function. Systems that do not perform network/PXE boot, or that do not rely on DHCP-supplied ROOT_PATH values, are not exposed to this issue.
Mitigation
Restrict DHCP server access on networks used for network boot (DHCP snooping, dedicated/trusted provisioning VLANs) until a fix is available.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Adjacent Network | N/A | Adjacent Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability,Non-Repudiation
Technical Impact: Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities
Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.
Acknowledgements
This issue was discovered by Pavel Valena (Red Hat).
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