What’s Vulnerable › Vulnerabilities

CVE-2026-93009: Dnsmasq: dnsmasq: heap out-of-bounds read in dhcpv6 option 39 fqdn decoder

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-29 · updated 2026-10-30
• Weakness: CWE-125

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.

Affected products

• Red Hat OpenShift Container Platform 4.18: all versions
• Red Hat Ceph Storage 9: all versions
• Red Hat Enterprise Linux 10: all versions
• Red Hat Enterprise Linux 6: all versions
• Red Hat Enterprise Linux 7: all versions
• Red Hat Enterprise Linux 8: all versions
• Red Hat Enterprise Linux 9: all versions
• Red Hat OpenShift Container Platform 5: all versions
• Red Hat OpenStack Platform 13 (Queens): all versions
• Red Hat OpenStack Platform 18.0: all versions

References

• https://access.redhat.com/security/cve/CVE-2026-93009
• https://bugzilla.redhat.com/show_bug.cgi?id=2536083

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