Open-iscsi: open-iscsi: integer underflow in iscsiuio dhcpv6 parsing
Published Aug 12, 2026
6.5
MEDIUMCVSS 3.1
EPSS 0.19%
Description
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.
Affected products
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||
|---|---|---|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | affected |
| |||
| Red Hat | Red Hat Enterprise Linux 9 | affected |
|
- 9.0
- 10.0
No data.
Red Hat Enterprise Linux 10
iscsi-initiator-utils
Fix deferred
Red Hat Enterprise Linux 9
iscsi-initiator-utils
Fix deferred
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | iscsi-initiator-utils | Fix deferred | n/a |
| Red Hat Enterprise Linux 9 | iscsi-initiator-utils | Fix deferred | n/a |
No package ranges for this CVE.
Remediation
Vendor solution
If DHCPv6 is not required for `iscsiuio`, disable DHCPv6 handling for the relevant network interface. If DHCPv6 is necessary, restrict network exposure to trusted adjacent networks and implement firewall rules to prevent forged DHCPv6 server traffic from reaching clients on shared L2 segments. A system restart or service reload may be required for changes to take effect.
Red Hat statement
This Moderate flaw in `iscsi-initiator-utils` can lead to an adjacent-network denial of service in the `iscsiuio` DHCPv6 client path. Exploitation requires an attacker on the same L2 segment to send crafted DHCPv6 Advertise traffic while the client is in an active DHCPv6 exchange, limiting its broader impact.
Red Hat mitigation
If DHCPv6 is not required for `iscsiuio`, disable DHCPv6 handling for the relevant network interface. If DHCPv6 is necessary, restrict network exposure to trusted adjacent networks and implement firewall rules to prevent forged DHCPv6 server traffic from reaching clients on shared L2 segments. A system restart or service reload may be required for changes to take effect.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Aug 13, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
Aug–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.19% (0.00188) | 7.62th | v5 (v2026.06.15) |
| Aug 13, 2026 | 0.20% (0.00197) | 9.64th | v5 (v2026.06.15) |
References (4)
- https://access.redhat.com/security/cve/CVE-2026-18727 vdb-entryx_refsource_REDHATVendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2462956 issue-trackingx_refsource_REDHATIssue TrackingVendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-18727
- https://www.cve.org/CVERecord?id=CVE-2026-18727
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2026-18727 | vdb-entryx_refsource_REDHATVendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2462956 | issue-trackingx_refsource_REDHATIssue TrackingVendor Advisory | |
| https://nvd.nist.gov/vuln/detail/CVE-2026-18727 | ||
| https://www.cve.org/CVERecord?id=CVE-2026-18727 |
Change history (0)
No recorded changes yet.