Medium [CVE-2026-18728] Integer underflow in iscsiuio IPv4 DHCP parsing
This medium-severity Red Hat Linux advisory covers CVE-2026-18728 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: iscsi-initiator-utils.
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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 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.
This flaw in `iscsi-initiator-utils` is rated Moderate. It allows an adjacent-network attacker to trigger a denial of service by sending a crafted IPv4/UDP DHCP reply to systems where `iscsiuio` is configured to use IPv4 DHCP.
Exploitation requires specific network conditions and a vulnerable configuration, limiting its broader impact. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-191. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: iscsi-initiator-utils.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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