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open-iscsi CVE-2026-18726

| EUVDEUVD-2026-57636 MEDIUM
Loop with Unreachable Exit Condition (Infinite Loop) (CWE-835)
2026-08-12 redhat GHSA-q9p8-qgxc-hw66
Buffer Overflow Denial Of Service Information Disclosure Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 9 Red Hat
6.5
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
6.5 MEDIUM
AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
6.5 MEDIUM

Adjacent-network vector confirmed by same-LAN-segment requirement; unauthenticated single-packet trigger; only availability impacted, no confidentiality or integrity effect confirmed.

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
6.5 MEDIUM
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Aug 12, 2026 - 21:55 vuln.today
CVE Published
Aug 12, 2026 - 21:13 cve.org
MEDIUM 6.5

DescriptionCVE.org

A flaw was found in open-iscsi. This vulnerability allows a remote attacker on the same local network segment to cause a Denial of Service (DoS) in the iscsiuio daemon. By sending a specially crafted Internet Control Message Protocol version 6 (ICMPv6) Router Advertisement with a zero-length option, the attacker can trigger an infinite loop. This leads to sustained CPU usage, rendering the daemon unresponsive and impacting system availability. A secondary risk of out-of-bounds reads exists with a short IPv6 payload, though no memory corruption or data exposure has been confirmed.

AnalysisAI

Denial of service in open-iscsi's iscsiuio daemon allows an unauthenticated attacker on the same local network segment to render the daemon permanently unresponsive by sending a single crafted ICMPv6 Router Advertisement carrying a zero-length option, triggering an infinite loop and sustained CPU exhaustion. Affected deployments include Red Hat Enterprise Linux 9 and 10 systems where iscsiuio is active for iSCSI hardware offload. A secondary out-of-bounds read risk exists when a short IPv6 payload is processed, though no memory corruption or data exposure has been confirmed from available intelligence; no public exploit code or CISA KEV listing has been identified at time of analysis.

Technical ContextAI

open-iscsi is the standard iSCSI initiator stack for Linux, enabling hosts to access remote block storage over IP networks. The iscsiuio daemon is a user-space component that supports iSCSI hardware offload (iSER/iSCSI over Ethernet), processing low-level network events including ICMPv6 messages. CWE-835 (Loop with Unreachable Exit Condition) identifies the root cause: the daemon's ICMPv6 Router Advertisement parser does not guard against a zero-length option field, causing the iteration logic to spin indefinitely without progress, consuming all available CPU. The secondary risk (OOB read on short IPv6 payload) aligns with the Buffer Overflow and Information Disclosure tags in the intelligence record, suggesting inadequate bounds checking during option traversal, though exploitation of that secondary path has not been confirmed. Affected CPE strings are cpe:2.3:a:red_hat:red_hat_enterprise_linux_9 and cpe:2.3:a:red_hat:red_hat_enterprise_linux_10, indicating the vulnerability is tracked against the Red Hat packaging of open-iscsi.

RemediationAI

No specific fixed package version is confirmed from the available references; monitor the Red Hat CVE advisory at https://access.redhat.com/security/cve/CVE-2026-18726 and Bugzilla ticket 2462331 for errata updates and apply the official RPM update for open-iscsi as soon as it is published via Red Hat's security channels. As a compensating control, restrict ICMPv6 Router Advertisement messages at the network boundary or host firewall using ip6tables or nftables rules targeting ICMPv6 type 134 (Router Advertisement) from untrusted LAN segments - note that legitimate IPv6 SLAAC and router discovery depend on RA messages, so blanket blocking may disrupt IPv6 autoconfiguration and should be scoped to untrusted VLANs. If iscsiuio is not required (i.e., the deployment does not use iSCSI hardware offload), disabling or stopping the iscsiuio service eliminates exposure entirely with no impact on software iSCSI initiator functionality. Network segmentation to ensure only trusted storage network hosts share the same L2 broadcast domain as iSCSI initiators is the most impactful architectural control.

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Same weakness CWE-835 – Loop with Unreachable Exit Condition (Infinite Loop)

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
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SLES15-SP6-CHOST-BYOS-Azure Affected
SLES15-SP6-CHOST-BYOS-EC2 Affected

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CVE-2026-18726 vulnerability details – vuln.today
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