CVE-2026-98493

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: ipconfig: bound DHCP option construction

ic_dhcp_init_options() appends the hostname (option 12), vendor-class

(option 60) and client-ID (option 61) options into the fixed 312-byte

bootp_pkt.exten[] buffer. Only the client-ID branch checked the

remaining space; the hostname and vendor-class writes were unbounded.

A 64-byte hostname together with the maximum 252-byte dhcpclass=

identifier needs 18 + (2 + 64) + (2 + 252) = 338 of the 312 available

bytes even before the terminating END marker, so the vendor-class memcpy

runs past the end of exten[]. With CONFIG_FORTIFY_SOURCE this is

reported as a field-spanning write and, when the kernel is booted with

panic_on_warn=1, aborts boot with a panic.

Route the optional options through a common helper that makes sure the

option, its 2-byte header and the END marker all fit and drops an option

that would not. Configurations with short options keep sending exactly

the

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References