{
  "threat_severity" : "Important",
  "public_date" : "2026-05-09T00:00:00Z",
  "bugzilla" : {
    "description" : "dnsmasq: RRSIG rdlen underflow leading to heap OOB read",
    "id" : "2458517",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2458517"
  },
  "cvss3" : {
    "cvss3_base_score" : "7.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-125",
  "details" : [ "A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.", "A heap out-of-bounds read vulnerability was discovered in dnsmasq's DNSSEC validation. When processing RRSIG records, dnsmasq calculates the signature length by subtracting the fixed field size from the record's declared data length. A crafted RRSIG record with a data length smaller than the fixed fields causes this calculation to underflow, potentially resulting in an out-of-bounds read and process crash." ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-05-19T00:00:00Z",
    "advisory" : "RHSA-2026:19158",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.2",
    "package" : "dnsmasq-0:2.90-7.el10_2"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-05-19T00:00:00Z",
    "advisory" : "RHSA-2026:19373",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "dnsmasq-0:2.85-18.el9_8.1"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Will not fix",
    "package_name" : "dnsmasq",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Affected",
    "package_name" : "dnsmasq",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Affected",
    "package_name" : "dnsmasq",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat OpenShift Container Platform 4",
    "fix_state" : "Affected",
    "package_name" : "rhcos",
    "cpe" : "cpe:/a:redhat:openshift:4"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-4891\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-4891\nhttps://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html" ],
  "name" : "CVE-2026-4891",
  "csaw" : false
}