CVE-2026-42511 Details
Description
The BOOTP file field is written to the lease file without escaping embedded double-quotes, allowing injection of arbitrary dhclient.conf directives. When the lease file is subsequently re-parsed by dhclient, e.g., after a system restart, an attacker-controlled field from the lease is passed to dhclient-script(8), which evaluates it. A rogue DHCP server may be able to execute arbirary code as root on a system running dhclient.
A remote code execution vulnerability has been identified in the dhclient utility, which is the default IPv4 DHCP client on FreeBSD. This issue affects all supported versions of FreeBSD. The vulnerability arises because the BOOTP file field is written to the lease file without properly escaping embedded double quotes. This flaw allows for the injection of arbitrary directives that can be executed by dhclient-script, potentially leading to the execution of malicious code as root. The vulnerability can be exploited by a rogue DHCP server on the same broadcast domain that responds to DHCP requests.
Users can upgrade to a supported FreeBSD stable or release branch dated after the correction date. Instructions for updating via the pkg utility, freebsd-update utility, or by applying a source code patch are available in the FreeBSD Security Advisory.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 1, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:12.dhclient.asc | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-149 | Improper Neutralization of Quoting Syntax | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| freebsd freebsd | 13.5 - 13.5 beta3 13.5 p1 13.5 p10 13.5 p11 13.5 p12 13.5 p2 13.5 p3 13.5 p4 13.5 p5 13.5 p6 13.5 p7 13.5 p8 13.5 p9 14.3 - 14.3 p1 14.3 p10 14.3 p11 14.3 p2 14.3 p3 14.3 p4 14.3 p5 14.3 p6 14.3 p7 14.3 p8 14.3 p9 14.4 - 14.4 p1 14.4 p2 14.4 rc1 15.0 - 15.0 p1 15.0 p2 15.0 p3 15.0 p4 15.0 p5 15.0 p6 |
CPE
Remediation
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Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 1, 2026 | CVE Modified | CISA-ADP |
| May 1, 2026 | Initial Analysis | [email protected] |
| Apr 30, 2026 | CVE Modified | CISA-ADP |
| Apr 30, 2026 | New CVE Received | [email protected] |