{
  "cveId": "CVE-2026-55717",
  "url": "https://patchblox.com/security/cve/CVE-2026-55717",
  "summary": "CVE-2026-55717 is fixed in 12 products on 1 platform, first by DEBIAN-CVE-2026-55717, released July 28, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "\u0027serve-expired-client-timeout\u0027 and \u0027response-ip\u0027 CNAME redirect could lead to a crash",
  "description": "In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when \u0027serve-expired: yes\u0027 is set together with a \u0027response-ip: \u003Cnet\u003E redirect\u0027 /\u0027response-ip-data: \u003Cnet\u003E CNAME \u003Ctarget\u003E\u0027 rule (or the RPZ \u0027rpz-cname-override\u0027 equivalent), a remote client who controls any delegated domain can crash the daemon. The serve-expired-client-timeout callback runs a two-pass loop to chase the respip-generated CNAME alias; on the second pass it resets \u0027alias_rrset\u0027 but not \u0027partial_rep\u0027. Later, this inconsistency leads to a NULL pointer dereference and an eventual crash. A malicious actor can exploit the vulnerability by controlling any zone that replies with an A/AAAA record that falls inside the configured response-ip/rpz subnet. By delaying the answer when the previous record has expired, the vulnerable path of \u0027serve-expired-client-timeout\u0027 is taken leading to denial of service via the server crash.",
  "published": "2026-07-22T14:17:21Z",
  "severity": "Moderate",
  "cvss": 5.9,
  "cvssVector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "cwe": "NULL Pointer Dereference",
  "epss": 0.00237,
  "epssPercentile": 0.14838,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55717",
  "fixes": [
    {
      "platform": "linux",
      "product": "python3-unbound",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "python3-unbound-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "1.26.1-0\u002Bdeb13u1",
      "fix": "DEBIAN-CVE-2026-55717",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-55717",
      "released": "2026-07-28T14:13:38Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "Debian 14",
      "fixedVersion": "1.25.2-1",
      "fix": "DEBIAN-CVE-2026-55717",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-55717",
      "released": "2026-07-28T14:13:38Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "opensuse-leap 16.0",
      "fixedVersion": "1.25.2-160000.1.1",
      "fix": "OPENSUSE-SU-2026:21550-1",
      "url": "https://patchblox.com/security/fix/linux/opensuse-su-2026-21550-1",
      "released": "2026-08-10T15:27:28Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "sles 15.6",
      "fixedVersion": "1.25.2-150600.23.19.1",
      "fix": "SUSE-SU-2026:3885-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-3885-1",
      "released": "2026-08-31T14:34:37Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "sles 15.7",
      "fixedVersion": "1.25.2-150600.23.19.1",
      "fix": "SUSE-SU-2026:3885-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-3885-1",
      "released": "2026-08-31T14:34:37Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "sles 16.0",
      "fixedVersion": "1.25.2-160000.1.1",
      "fix": "SUSE-SU-2026:23226-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-23226-1",
      "released": "2026-08-10T15:26:22Z"
    },
    {
      "platform": "linux",
      "product": "unbound-anchor",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-anchor-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-debugsource",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-devel",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-libs",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-libs-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-utils",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "unbound-utils-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1.17.1-1.amzn2023.0.13",
      "fix": "ALAS2023-2026-2033",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-2033",
      "released": "2026-08-03T09:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}