CVE-2026-98493
Received
Received - Intake
Heap Buffer Overflow in Linux Kernel DHCP Option Handling
Vulnerability report for CVE-2026-98493, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-18
Last updated on: 2026-10-18
Assigner: kernel.org
Description
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 same bytes as before.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | 130c0f47fdf9c533deb1136cad5136f6cb7020f0 |
| Linux | Linux | 130c0f47fdf9c533deb1136cad5136f6cb7020f0 |
| Linux | Linux | 130c0f47fdf9c533deb1136cad5136f6cb7020f0 |
| Linux | Linux | 130c0f47fdf9c533deb1136cad5136f6cb7020f0 |
| Linux | Linux | 2.6.36 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
