CVE-2026-18728 Red Hat CVE debrief

Who should care

System administrators and security teams responsible for open-iscsi installations, especially those handling IPv4 DHCP traffic, should be aware of this vulnerability. Red Hat Enterprise Linux users should verify their systems' exposure and apply patches or mitigations as necessary.

Technical summary

CVE-2026-18728 is an integer underflow vulnerability in the `iscsiuio` component of open-iscsi, occurring during IPv4 DHCP parsing. A remote attacker on the same local network segment can exploit this by sending a specially crafted IPv4/UDP DHCP reply, triggering an out-of-bounds read that causes the `iscsiuio` process to crash, leading to a denial of service. This issue affects systems where `iscsiuio` is actively handling IPv4 DHCP traffic.

Defensive priority

Medium-priority defensive actions are recommended due to the CVSS score of 6.5 and the potential for denial of service.

Recommended defensive actions

• Verify if open-iscsi is installed and running on your systems, especially those handling IPv4 DHCP traffic.
• Check for and apply any available patches or updates from the vendor.
• Monitor network traffic for suspicious IPv4 DHCP activity.
• Implement compensating controls, such as network segmentation or traffic filtering, if patching is not immediately feasible.
• Review system logs for signs of exploitation attempts.

Evidence notes

The CVE-2026-18728 record indicates an integer underflow vulnerability in the `iscsiuio` component of open-iscsi, specifically during IPv4 DHCP parsing. This allows a remote attacker on the same local network segment to cause a denial of service by triggering an out-of-bounds read, leading to the `iscsiuio` process crashing. The issue affects systems where `iscsiuio` is actively handling IPv4 DHCP traffic. Further verification of affected systems and vendor remediation efforts is recommended.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.