{
  "cveId": "CVE-2026-41637",
  "url": "https://patchblox.com/security/cve/CVE-2026-41637",
  "summary": "CVE-2026-41637 is fixed in unbound on 1 platform, first by DEBIAN-CVE-2026-41637, released July 28, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "Degradation of resolution service from improperly accounted client-terminated DNS-over-QUIC queries",
  "description": "In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, client terminated DNS-over-QUIC (DoQ) queries are not accounted properly by Unbound resulting in low-cost inflation of the waiting number of replies for already in-flight resolution queries. This results in degradation of resolution service for new clients for already in-flight queries. A malicious actor can exploit the vulnerability by issuing DoQ queries for query names that need resolution and proceeding on immediately terminating the query by one of STOP_SENDING/RESET_STREAM/CONNECTION_CLOSE QUIC frames. Those terminated DoQ queries are not properly counted for and keep inflating the number of waiting replies for in-flight queries. When the maximum is reached, it results in silent query drops for new clients needing resolution for already in-flight queries. This vulnerability needs Unbound to be compiled with DoQ support (\u0027--with-libngtcp2\u0027) and the \u0027quic-port\u0027 to be configured for the listening interfaces. Additionally, a malicious actor needs access to multiple source IPs to bypass the by-default configured \u0027wait-limit\u0027 option.",
  "published": "2026-07-22T14:17:18Z",
  "severity": "Low",
  "cvss": 3.7,
  "cvssVector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
  "cwe": "Missing Release of Resource after Effective Lifetime",
  "epss": 0.00368,
  "epssPercentile": 0.30923,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41637",
  "fixes": [
    {
      "platform": "linux",
      "product": "unbound",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "1.26.1-0\u002Bdeb13u1",
      "fix": "DEBIAN-CVE-2026-41637",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-41637",
      "released": "2026-07-28T14:13:38Z"
    },
    {
      "platform": "linux",
      "product": "unbound",
      "release": "Debian 14",
      "fixedVersion": "1.25.2-1",
      "fix": "DEBIAN-CVE-2026-41637",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-41637",
      "released": "2026-07-28T14:13:38Z"
    },
    {
      "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 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"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}