---
id: CVE-2026-18728
title: 'Open-iscsi: open-iscsi: integer underflow in iscsiuio ipv4 dhcp parsing'
summary: >-
  A flaw was found in open-iscsi. An integer underflow vulnerability in the
  `iscsiuio` component, specifically during IPv4 Dynamic Host Configuration
  Protocol (DHCP) parsing, allows a remote attacker on the same local network
  segment to ca…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-191
vendor: Red Hat
product: iscsi-initiator-utils
affected:
  - iscsi-initiator-utils (all versions)
  - iscsi-initiator-utils (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-14T22:24:09.250067Z'
published: '2026-08-13'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T19:25:54.281Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-18728'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-18728'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2463029'
    label: RHBZ#2463029
tags:
  - cve.org
epss: 0.00312
epssPercentile: 0.24276
ingestedAt: '2026-11-05T22:38:31.542Z'
---

## Overview

A flaw was found in open-iscsi. An integer underflow vulnerability in the `iscsiuio` component, specifically during IPv4 Dynamic Host Configuration Protocol (DHCP) parsing, allows a remote attacker on the same local network segment to cause a denial of service. By sending a specially crafted IPv4/UDP DHCP reply, the attacker can trigger an out-of-bounds read, leading to the `iscsiuio` process crashing. This issue affects systems where `iscsiuio` is actively handling IPv4 DHCP traffic.

## Affected

- `iscsi-initiator-utils (all versions)`
- `iscsi-initiator-utils (all versions)`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

To mitigate this issue, restrict network access to `iscsiuio`-managed interfaces. Configure firewall rules to limit DHCP/BOOTP traffic to only trusted infrastructure within the local broadcast domain. This reduces the exposure to untrusted systems that could send crafted IPv4 DHCP packets. If `iscsiuio` is actively using IPv4 DHCP, consider reconfiguring it to use static IP addresses or a different network configuration if feasible. Changes to network configuration may require a service restart.