{
  "cveId": "CVE-2026-63387",
  "url": "https://patchblox.com/security/cve/CVE-2026-63387",
  "summary": "CVE-2026-63387 is fixed in 8 products on 1 platform, first by libevent-2.1-7t64 2.1.12-stable-10ubuntu0.2, released August 20, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response",
  "description": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.",
  "published": "2026-08-20T11:16:00Z",
  "severity": "Moderate",
  "cvss": 8.6,
  "cvssVector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H",
  "cwe": "Stack-based Buffer Overflow",
  "epss": 0.00416,
  "epssPercentile": 0.36147,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63387",
  "fixes": [
    {
      "platform": "linux",
      "product": "libevent",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "2.1.12-stable-8\u002Bdeb12u1",
      "fix": "DEBIAN-CVE-2026-63387",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63387",
      "released": "2026-08-21T23:37:15Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "2.1.13-stable-1~deb13u1",
      "fix": "DEBIAN-CVE-2026-63387",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63387",
      "released": "2026-08-21T23:37:15Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "Debian 14",
      "fixedVersion": "2.1.13-stable-1",
      "fix": "DEBIAN-CVE-2026-63387",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63387",
      "released": "2026-08-21T23:37:15Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "RHEL 10",
      "fixedVersion": "2.1.13-1.el10_2",
      "fix": "RHSA-2026:67909",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67909",
      "released": "2026-09-17T18:11:06Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "RHEL 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "RHSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67908",
      "released": "2026-09-19T18:31:30Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "RHEL 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "RHSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67910",
      "released": "2026-09-19T18:32:55Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "almalinux 10",
      "fixedVersion": "2.1.13-1.el10_2",
      "fix": "ALSA-2026:67909",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "almalinux 8",
      "fixedVersion": "2.1.8-11.el8_10",
      "fix": "ALSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67908",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "almalinux 9",
      "fixedVersion": "2.1.13-1.el9_8",
      "fix": "ALSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "ol 10",
      "fixedVersion": "0:2.1.13-1.el10_2",
      "fix": "ELSA-2026-67909",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "ol 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "ELSA-2026-67908",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67908",
      "released": "2026-09-17T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "ol 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "ELSA-2026-67910",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "rocky 10",
      "fixedVersion": "0:2.1.13-1.el10_2",
      "fix": "RLSA-2026:67909",
      "url": "https://patchblox.com/security/fix/linux/rlsa-2026-67909",
      "released": "2026-09-17T12:09:45Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "rocky 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "RLSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/rlsa-2026-67908",
      "released": "2026-09-17T12:01:09Z"
    },
    {
      "platform": "linux",
      "product": "libevent",
      "release": "rocky 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "RLSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/rlsa-2026-67910",
      "released": "2026-09-17T06:06:39Z"
    },
    {
      "platform": "linux",
      "product": "libevent-2.1-7t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "2.1.12-stable-10ubuntu0.2",
      "fix": "libevent-2.1-7t64 2.1.12-stable-10ubuntu0.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libevent-2.1-7t64-2.1.12-stable-10ubuntu0.2",
      "released": "2026-08-20T11:16:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-core-2.1-7t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "2.1.12-stable-10ubuntu0.2",
      "fix": "libevent-core-2.1-7t64 2.1.12-stable-10ubuntu0.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libevent-core-2.1-7t64-2.1.12-stable-10ubuntu0.2",
      "released": "2026-08-20T11:16:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "RHEL 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "RHSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67908",
      "released": "2026-09-19T18:31:30Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "RHEL 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "RHSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67910",
      "released": "2026-09-19T18:32:55Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "almalinux 10",
      "fixedVersion": "2.1.13-1.el10_2",
      "fix": "ALSA-2026:67909",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "almalinux 8",
      "fixedVersion": "2.1.8-11.el8_10",
      "fix": "ALSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67908",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "almalinux 9",
      "fixedVersion": "2.1.13-1.el9_8",
      "fix": "ALSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "ol 10",
      "fixedVersion": "0:2.1.13-1.el10_2",
      "fix": "ELSA-2026-67909",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "ol 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "ELSA-2026-67908",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67908",
      "released": "2026-09-17T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-devel",
      "release": "ol 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "ELSA-2026-67910",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "RHEL 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "RHSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67908",
      "released": "2026-09-19T18:31:30Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "RHEL 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "RHSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67910",
      "released": "2026-09-19T18:32:55Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "almalinux 10",
      "fixedVersion": "2.1.13-1.el10_2",
      "fix": "ALSA-2026:67909",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "almalinux 8",
      "fixedVersion": "2.1.8-11.el8_10",
      "fix": "ALSA-2026:67908",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67908",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "almalinux 9",
      "fixedVersion": "2.1.13-1.el9_8",
      "fix": "ALSA-2026:67910",
      "url": "https://patchblox.com/security/fix/linux/alsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "ol 10",
      "fixedVersion": "0:2.1.13-1.el10_2",
      "fix": "ELSA-2026-67909",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67909",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "ol 8",
      "fixedVersion": "0:2.1.8-11.el8_10",
      "fix": "ELSA-2026-67908",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67908",
      "released": "2026-09-17T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-doc",
      "release": "ol 9",
      "fixedVersion": "0:2.1.13-1.el9_8",
      "fix": "ELSA-2026-67910",
      "url": "https://patchblox.com/security/fix/linux/elsa-2026-67910",
      "released": "2026-09-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-extra-2.1-7t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "2.1.12-stable-10ubuntu0.2",
      "fix": "libevent-extra-2.1-7t64 2.1.12-stable-10ubuntu0.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libevent-extra-2.1-7t64-2.1.12-stable-10ubuntu0.2",
      "released": "2026-08-20T11:16:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-openssl-2.1-7t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "2.1.12-stable-10ubuntu0.2",
      "fix": "libevent-openssl-2.1-7t64 2.1.12-stable-10ubuntu0.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libevent-openssl-2.1-7t64-2.1.12-stable-10ubuntu0.2",
      "released": "2026-08-20T11:16:00Z"
    },
    {
      "platform": "linux",
      "product": "libevent-pthreads-2.1-7t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "2.1.12-stable-10ubuntu0.2",
      "fix": "libevent-pthreads-2.1-7t64 2.1.12-stable-10ubuntu0.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libevent-pthreads-2.1-7t64-2.1.12-stable-10ubuntu0.2",
      "released": "2026-08-20T11:16:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T13:31:49Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}