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CVE-2026-93009medium4.3

Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder

Impact

A heap out-of-bounds read flaw in dnsmasq's DHCPv6 client hostname parser can be triggered by an attacker on the local network with a crafted FQDN option. The impact is unclear. Affected products include various Red Hat Enterprise Linux and OpenShift Container Platform versions.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

What to do

The following measures reduce risk:

  1. If DHCPv6 is not required, do not configure any IPv6 dhcp-range.
  2. Compile without DHCPv6 using COPTS=-DNO_DHCP6 if IPv6 DHCP is not needed.
  3. Restrict dnsmasq to trusted interfaces with --interface=<iface>.
redhat guidance

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Red Hat · redhat

Red Hat Ceph Storage 9

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:ceph_storage:9

Red Hat · redhat

Red Hat Enterprise Linux 10

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/o:redhat:enterprise_linux:10

Red Hat · redhat

Red Hat Enterprise Linux 6

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/o:redhat:enterprise_linux:6

Red Hat · redhat

Red Hat Enterprise Linux 7

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/o:redhat:enterprise_linux:7

Red Hat · redhat

Red Hat Enterprise Linux 8

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/o:redhat:enterprise_linux:8

Red Hat · redhat

Red Hat Enterprise Linux 9

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/o:redhat:enterprise_linux:9

Red Hat · redhat

Red Hat OpenShift Container Platform 4

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:4

Red Hat · redhat

Red Hat OpenShift Container Platform 4

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:4

Red Hat · redhat

Red Hat OpenShift Container Platform 4

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:4

Red Hat · redhat

Red Hat OpenShift Container Platform 4

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:4

Red Hat · redhat

Red Hat OpenShift Container Platform 5

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:5

Red Hat · redhat

Red Hat OpenShift Container Platform 5

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openshift:5

Red Hat · redhat

Red Hat OpenStack Platform 13 (Queens)

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openstack:13

Red Hat · redhat

Red Hat OpenStack Platform 18.0

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:openstack:18.0

Original source description

A flaw was found in dnsmasq. The DHCPv6 client hostname parser can read one byte past the end of a crafted FQDN option because it checks the next label length before confirming the pointer is still inside the option. An attacker on the local network can trigger this with a single DHCPv6 packet. The extra byte is not returned to the client or logged, and no crash has been demonstrated.

Inside the record

Evidence available

Package identity · not supplied
Version evidence · not supplied
Remediation guidance
Weakness classification
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-93009

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-125 ↗

Out-of-bounds Read

redhat

Related →
Contributing organizations · 1
redhat

Assigning organization

2026-10-30

What changed

Follow changes
  1. CVE · CVE-2026-93009

    Observed 2026-10-30T08:11:05.075Z · upstream updated 2026-10-30T08:05:48.784Z

    Product or version evidence changed

    before

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  },
  {
    "vendor": "Red Hat",
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    ],
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 6",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 7",
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    "defaultStatus": "affected",
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    ],
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 8",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
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      "cpe:/o:redhat:enterprise_linux:8"
    ],
    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 9",
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      "cpe:/o:redhat:enterprise_linux:9"
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    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
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    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openshift:4"
    ],
    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenStack Platform 13 (Queens)",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openstack:13"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenStack Platform 18.0",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openstack:18.0"
    ],
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  }
]

    after

    [
  {
    "vendor": "Red Hat",
    "name": "Red Hat Ceph Storage 9",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:ceph_storage:9"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 10",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:10"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 6",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:6"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 7",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/o:redhat:enterprise_linux:7"
    ],
    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 8",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
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      "cpe:/o:redhat:enterprise_linux:8"
    ],
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat Enterprise Linux 9",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
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    "cpes": [
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  },
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  },
  {
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    ],
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 4",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
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    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 5",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openshift:5"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenShift Container Platform 5",
    "platforms": [],
    "versions": [],
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    "cpes": [
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    "source": "redhat",
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  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenStack Platform 13 (Queens)",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openstack:13"
    ],
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    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  },
  {
    "vendor": "Red Hat",
    "name": "Red Hat OpenStack Platform 18.0",
    "platforms": [],
    "versions": [],
    "defaultStatus": "affected",
    "cpes": [
      "cpe:/a:redhat:openstack:18.0"
    ],
    "source": "redhat",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-93009"
  }
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.

References

2 sources
access.redhat.com/security/cve/CVE-2026-93009
vdb-entryredhat
bugzilla.redhat.com/show_bug.cgi
issue-trackingredhat