{"id":"CVE-2026-93009","title":"Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder","summary":"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 l…","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","cvssSource":"cna","cwe":["CWE-125"],"vendor":"Red Hat","product":"rhceph/alloy-rhel10","affected":["rhceph/alloy-rhel10 (all versions)","dnsmasq (all versions)","dnsmasq (all versions)","dnsmasq (all versions)","dnsmasq (all versions)","dnsmasq (all versions)","openshift4/ose-baremetal-runtimecfg-rhel8 (all versions)","openshift4/ose-baremetal-runtimecfg-rhel9 (all versions)","openshift/ose-rhel-coreos-8 (all versions)","openshift/ose-rhel-coreos-9 (all versions)","openshift5/ose-baremetal-runtimecfg-rhel9 (all versions)","openshift/ose-rhel-coreos-9 (all versions)","dnsmasq (all versions)","rhoso-operators/infra-rhel9-operator (all versions)"],"published":"2026-10-29","updated":"2026-10-30","sourceUpdated":"2026-10-30T08:05:48.784Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-93009","references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-93009"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536083","label":"RHBZ#2536083"}],"tags":["cve.org"],"epss":0.00202,"epssPercentile":0.10211,"ingestedAt":"2026-11-03T10:42:03.632Z","slug":"CVE-2026-93009","body":"## Overview\n\nA 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.\n\n## Affected\n\n- `rhceph/alloy-rhel10 (all versions)`\n- `dnsmasq (all versions)`\n- `dnsmasq (all versions)`\n- `dnsmasq (all versions)`\n- `dnsmasq (all versions)`\n- `dnsmasq (all versions)`\n- `openshift4/ose-baremetal-runtimecfg-rhel8 (all versions)`\n- `openshift4/ose-baremetal-runtimecfg-rhel9 (all versions)`\n- `openshift/ose-rhel-coreos-8 (all versions)`\n- `openshift/ose-rhel-coreos-9 (all versions)`\n- `openshift5/ose-baremetal-runtimecfg-rhel9 (all versions)`\n- `openshift/ose-rhel-coreos-9 (all versions)`\n- `dnsmasq (all versions)`\n- `rhoso-operators/infra-rhel9-operator (all versions)`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n### Workarounds\n\nThe following measures reduce risk:\n\n1. If DHCPv6 is not required, do not configure any IPv6 dhcp-range.\n2. Compile without DHCPv6 using COPTS=-DNO_DHCP6 if IPv6 DHCP is not needed.\n3. Restrict dnsmasq to trusted interfaces with --interface=<iface>.","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}