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CVE-2026-18728

Open-iscsi: open-iscsi: integer underflow in iscsiuio ipv4 dhcp parsing

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.31%Up 0.1 points since Aug 13, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.5

Open-iscsi: open-iscsi: integer underflow in iscsiuio ipv4 dhcp parsing

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.

Record
CVE-2026-18728
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-191
Updated
2026-11-05
EUVDEUVD-2026-57715 6.5

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.

Record
EUVD-2026-57715
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-05
GitHub AdvisoriesGHSA-v5q9-q65g-v5rv 6.5

A flaw was found in open-iscsi. An integer underflow vulnerability in the `iscsiuio` component,...

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.

Record
GHSA-v5q9-q65g-v5rv
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-191
Updated
2026-11-02
NVD 6.5

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.

Record
CVE-2026-18728
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-191
Updated
2026-11-05
OSVDEBIAN-CVE-2026-18728 6.5

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.

Record
DEBIAN-CVE-2026-18728
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2026-3511 7.6

open-iscsi security update

The Open-iSCSI project is a high-performance, transport independent, multi-platform implementation of RFC3720 iSCSI.

Security Fix(es):

A stack buffer overflow vulnerability exists in the idbm_recinfo_config() function in open-iscsi (iscsi-initiator-utils). An attacker can craft a malicious SendTargets TargetName containing newline characters and oversized injected keys or values to inject extra configuration lines into persisted node records. When the record is reparsed, due to missing bounds checking, a stack buffer overflow occurs, leading to denial of service or potential memory corruption. The affected component is usr/idbm.c:idbm_recinfo_config in iscsi-initiator-utils, with attacker-controlled input reaching it through SendTargets handling in usr/discovery.c.(CVE-2026-18724)

A vulnerability was found in open-iscsi. In the ICMPv6 echo-reply path of iscsiuio, the code reuses the inbound ipv6_plen field when sizing the reply instead of clamping it to the bytes actually received. An attacker can send a crafted ICMPv6 Echo Request to trigger out-of-bounds reads and a potential one-byte out-of-bounds write, which may impact confidentiality, integrity, and availability.(CVE-2026-18725)

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.(CVE-2026-18726)

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.(CVE-2026-18727)

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.(CVE-2026-18728)

Record
OESA-2026-3511
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-18728 6.5

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.

Record
UBUNTU-CVE-2026-18728
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVAZL-95919 No score

CVE-2026-18728 affecting package iscsi-initiator-utils 2.1.12-1

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.

Record
AZL-95919
Updated
2026-11-05
OSVopenSUSE-SU-2026:12102-1 No score

iscsiuio-0.7.8.8-114.1 on GA media

These are all security issues fixed in the iscsiuio-0.7.8.8-114.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:12102-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
iscsi-initiator-utils
Azure Linux:3
through 2.1.12-1 None known
open-iscsi
Debian:12
before 2.1.8-1+deb12u1, plus listed versions
2.1.8-1
2.1.8-1+deb12u1
open-iscsi
Debian:13
All versions, plus listed versions
2.1.11-12.1.11-1+deb13u12.1.11-1+deb13u22.1.11-22.1.11-3
Show 6 moreShow less
2.1.11-42.1.11-52.1.11-62.1.12-12.1.12-22.1.13-1
None known
open-iscsi
Debian:14
before 2.1.13-1, plus listed versions
2.1.11-12.1.11-22.1.11-32.1.11-42.1.11-52.1.11-62.1.12-12.1.12-2
2.1.13-1
open-iscsi
openEuler:20.03-LTS-SP4
From an advisory covering 5 CVEs
before 2.1.1-18.oe2003sp4
2.1.1-18.oe2003sp4
open-iscsi
Ubuntu:14.04:LTS
All versions, plus listed versions
2.0.873-3ubuntu72.0.873-3ubuntu82.0.873-3ubuntu9
None known
open-iscsi
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
2.0.873-3ubuntu132.0.873+git0.3b4b4500-13ubuntu32.0.873+git0.3b4b4500-14ubuntu12.0.873+git0.3b4b4500-14ubuntu32.0.873+git0.3b4b4500-14ubuntu3.1
Show 7 moreShow less
2.0.873+git0.3b4b4500-14ubuntu3.22.0.873+git0.3b4b4500-14ubuntu3.32.0.873+git0.3b4b4500-14ubuntu3.42.0.873+git0.3b4b4500-14ubuntu3.52.0.873+git0.3b4b4500-14ubuntu3.62.0.873+git0.3b4b4500-14ubuntu3.72.0.873+git0.3b4b4500-14ubuntu3.7+esm1
None known
open-iscsi
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
2.0.874-4ubuntu32.0.874-4ubuntu42.0.874-4ubuntu52.0.874-5ubuntu12.0.874-5ubuntu2
Show 10 moreShow less
2.0.874-5ubuntu2.12.0.874-5ubuntu2.22.0.874-5ubuntu2.32.0.874-5ubuntu2.42.0.874-5ubuntu2.62.0.874-5ubuntu2.72.0.874-5ubuntu2.92.0.874-5ubuntu2.102.0.874-5ubuntu2.112.0.874-5ubuntu2.11+esm1
None known
open-iscsi
Ubuntu:20.04:LTS
All versions, plus listed versions
2.0.874-7.1ubuntu32.0.874-7.1ubuntu52.0.874-7.1ubuntu62.0.874-7.1ubuntu6.12.0.874-7.1ubuntu6.22.0.874-7.1ubuntu6.32.0.874-7.1ubuntu6.42.0.874-7.1ubuntu6.5
None known
open-iscsi
Ubuntu:22.04:LTS
All versions, plus listed versions
2.1.4-0ubuntu12.1.4-0ubuntu22.1.4-0ubuntu32.1.4-0ubuntu42.1.5-1ubuntu12.1.5-1ubuntu1.12.1.5-1ubuntu1.3
None known
Show 4 moreShow less
Affected packages
PackageAffectedFixed
open-iscsi
Ubuntu:24.04:LTS
All versions, plus listed versions
2.1.8-1ubuntu22.1.9-3ubuntu12.1.9-3ubuntu22.1.9-3ubuntu32.1.9-3ubuntu4
Show 5 moreShow less
2.1.9-3ubuntu5.12.1.9-3ubuntu5.22.1.9-3ubuntu5.32.1.9-3ubuntu5.42.1.9-3ubuntu5.5
None known
open-iscsi
Ubuntu:26.10
All versions, plus listed versions
2.1.11-3ubuntu32.1.11-5ubuntu12.1.11-5ubuntu42.1.11-5ubuntu52.1.11-5ubuntu6
None known
open-iscsi
Ubuntu:26.04:LTS
All versions, plus listed versions
2.1.11-1ubuntu32.1.11-3ubuntu12.1.11-3ubuntu22.1.11-3ubuntu32.1.11-3ubuntu3.1
None known
open-iscsi
openSUSE:Tumbleweed
From an advisory covering 5 CVEs
before 2.1.13-114.1
2.1.13-114.1

History

History
RecordedChangedSources
affected
referencesCVE List, EUVD, NVD
factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-18728 is a medium vulnerability (CVSS 6.5) in Red Hat Enterprise Linux 10, published August 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. Fixed in open-iscsi 2.1.8-1+deb12u1.

References

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