CVE-2026-18727: Open-iscsi: open-iscsi: integer underflow in iscsiuio dhcpv6 parsing

mediumCVSS 6.5CVE-2026-18727

CSIRTS triage

vendor: open-iscsi product: open-iscsi Memory corruption

What: An integer underflow in iscsiuio DHCPv6 parsing causes memory corruption and potential code execution.
Who is affected: Deployments running open-iscsi with DHCPv6 configuration enabled.
Urgency: Medium severity; requires specific DHCPv6 scenario but memory corruption is serious.
Action: Update open-iscsi to a patched version when available or disable DHCPv6 if not required.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 6.5
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18727

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-187270.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 10% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-18727	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

mediumCVE-2026-18727: A flaw was found in open-iscsi's iscsiuio component. This vulnerability involves an integer un…nvd

Recent advisories for Open-iscsi

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[NEW] [high] Red Hat Enterprise Linux (open-iscsi): Multiple vulnerabilitiescert-bund · 2026-08-20
medium[NEW] [medium] Red Hat Enterprise Linux (open-iscsi): Vulnerability Enables Denial of Servicecert-bund · 2026-08-18
mediumCVE-2026-18728: A flaw was found in open-iscsi. An integer underflow vulnerability in the `iscsiuio` component…nvd · 2026-08-13
mediumCVE-2026-18727: A flaw was found in open-iscsi's iscsiuio component. This vulnerability involves an integer un…nvd · 2026-08-12
mediumCVE-2026-18726: A flaw was found in open-iscsi. This vulnerability allows a remote attacker on the same local …nvd · 2026-08-12
mediumCVE-2026-18728: Open-iscsi: open-iscsi: integer underflow in iscsiuio ipv4 dhcp parsingmsrc · 2026-08-11