# CVE-2026-18728: Open-iscsi: open-iscsi: integer underflow in iscsiuio ipv4 dhcp parsing

CVE-2026-18728 is fixed in 9 products on 1 platform, first by DEBIAN-CVE-2026-18728, released August 13, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-18728
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0031
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 13, 2026
- Weakness: Integer Underflow (Wrap or Wraparound)
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18728

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | iscsi-initiator-utils amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-debugsource amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-devel amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-iscsiuio amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-iscsiuio-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | open-iscsi Debian 12.15 (bookworm) | 2.1.8-1+deb12u1 | [DEBIAN-CVE-2026-18728](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18728.md) | Aug 13, 2026 |
| Linux | open-iscsi Debian 14 | 2.1.13-1 | [DEBIAN-CVE-2026-18728](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18728.md) | Aug 13, 2026 |
| Linux | python3-iscsi-initiator-utils amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | python3-iscsi-initiator-utils-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |

---

Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.