CVE-2026-18727

Open-iscsi: open-iscsi: integer underflow in iscsiuio dhcpv6 parsing

CVE-2026-18727 is fixed in 9 products on 1 platform, first by DEBIAN-CVE-2026-18727, released August 12, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

6.5

Moderate

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0029

21st percentile

A flaw was found in open-iscsi's iscsiuio component. This vulnerability involves an integer underflow and out-of-bounds read during Dynamic Host Configuration Protocol for IPv6 (DHCPv6) packet parsing. Specifically, crafted DHCPv6 Advertise traffic with a short User Datagram Protocol (UDP) length can cause the DHCPv6 payload length to underflow. An unauthenticated attacker on an adjacent network segment can exploit this by sending specially crafted IPv6 UDP traffic while the client is in an active DHCPv6 exchange, leading to a denial of service due to a process crash or service disruption.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
iscsi-initiator-utils · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
iscsi-initiator-utils-debuginfo · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
iscsi-initiator-utils-debugsource · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
iscsi-initiator-utils-devel · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
iscsi-initiator-utils-iscsiuio · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
iscsi-initiator-utils-iscsiuio-debuginfo · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
open-iscsi · Debian 12.15 (bookworm)	2.1.8-1+deb12u1	DEBIAN-CVE-2026-18727	Aug 12, 2026
open-iscsi · Debian 14	2.1.13-1	DEBIAN-CVE-2026-18727	Aug 12, 2026
python3-iscsi-initiator-utils · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026
python3-iscsi-initiator-utils-debuginfo · amzn 2023	6.2.1.4-10.git2a8f9d8.amzn2023.0.4	ALAS2023-2026-2120	Aug 31, 2026

Details

Published
August 12, 2026
Weakness
Integer Underflow (Wrap or Wraparound)
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18727

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