{"id":"CVE-2026-32665","title":"unbound: Unbound: Denial of Service via improper validation of DNS-over-QUIC client length (CVE-2026-32665)","summary":"A flaw was found in Unbound when DNS-over-QUIC (DoQ) is enabled. An attacker could exploit improper validation of client-provided data length, leading to excessive memory allocation. This can cause the system to exceed its configured memor…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-770","CWE-1284"],"vendor":"Red Hat","product":"Red Hat Hardened Images","affected":["hardened_images"],"patched":["hardened_images"],"published":"2026-07-22","updated":"2026-10-23","sourceUpdated":"2026-10-23T17:23:49+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32665.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32665.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-32665"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2503060"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-32665"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32665"},{"url":"https://access.redhat.com/errata/RHSA-2026:43588"},{"url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-32665.txt"}],"tags":["csaf","vex","red-hat","cve.org"],"epss":0.00285,"epssPercentile":0.20868,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-07-22T14:31:54.691586Z"},"ingestedAt":"2026-09-16T14:57:28.057Z","slug":"CVE-2026-32665","body":"## Overview\n\nA flaw was found in Unbound when DNS-over-QUIC (DoQ) is enabled. An attacker could exploit improper validation of client-provided data length, leading to excessive memory allocation. This can cause the system to exceed its configured memory limits for QUIC connections, resulting in a Denial of Service (DoS) for new DoQ clients.\n\n## Vendor advisories\n\n- **RHSA-2026:43588** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:43588)\n\n**unbound: Unbound: Denial of Service via improper validation of DNS-over-QUIC client length** — rated Important by Red Hat. Released 2026-07-22, updated 2026-10-23.\n\nFixed:\n\n- Red Hat Hardened Images\n\nNot affected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\n## Remediation\n\nFor details on how to apply this update, which includes the changes described in this advisory, refer to:\nhttps://images.redhat.com/ https://access.redhat.com/errata/RHSA-2026:43588\n\nWorkarounds / mitigations:\n\n- To mitigate this issue, disable DNS-over-QUIC (DoQ) in the Unbound configuration if it is not a required service. This can typically be achieved by commenting out or removing DoQ-related configuration options in `unbound.conf`. For example, remove or comment out lines such as `do-quic: yes` or `quic-port: 853`.\n\nAfter modifying the configuration, restart the Unbound service for the changes to take effect:\n```bash\nsystemctl restart unbound\n```\nWarning: Restarting the Unbound service will tempora…","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}