CVE-2026-93009
Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder
- Published
- Updated
- Reserved
- Assigned by
- redhat
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Awaiting Analysis | 3.1 | Medium4.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.20% · top 90% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Weakness
Affected products
Red Hat · Red Hat Ceph Storage 9
All versions: affected
Red Hat · Red Hat Enterprise Linux 10
All versions: affected
Red Hat · Red Hat Enterprise Linux 6
All versions: affected
Red Hat · Red Hat Enterprise Linux 7
All versions: affected
Red Hat · Red Hat Enterprise Linux 8
All versions: affected
Red Hat · Red Hat Enterprise Linux 9
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 4
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 5
All versions: affected
Red Hat · Red Hat OpenShift Container Platform 5
All versions: affected
Red Hat · Red Hat OpenStack Platform 13 (Queens)
All versions: affected
Red Hat · Red Hat OpenStack Platform 18.0
All versions: affected
What to do
Workaround: 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>.
References (2)
- https://access.redhat.com/security/cve/CVE-2026-93009 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2536083 (opens in a new tab)issue-trackingx_refsource_REDHAT
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-93009)Record last updated .