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Fencer Vulns
medium 6.5

CVE-2026-18727 json

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

published 2026-08-12 2 mo ago modified 2026-11-05 3 d ago also EUVD-2026-57637

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

Summary

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.

Patch / fix

  • open-iscsi Debian 12 2.1.8-1+deb12u1
  • open-iscsi Debian 14 2.1.13-1

debian advisories DEBIAN-CVE-2026-18727

  • open-iscsi openSUSE Tumbleweed 2.1.13-114.1

opensuse advisories openSUSE-SU-2026:12102-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-18727 updated cvss 6.5

open-iscsi: open-iscsi: Integer underflow in iscsiuio DHCPv6 parsing

  • Red Hat Enterprise Linux 9 iscsi-initiator-utils, python3-iscsi-initiator-utils, iscsi-initiator-utils-iscsiuio Red Hat Enterprise Linux 10 iscsi-initiator-utils
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.