CVE-2026-4891 (GCVE-0-2026-4891)
Vulnerability from cvelistv5
Published
2026-05-11 16:47
Modified
2026-08-25 12:05
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
Summary
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.
References
Impacted products
Vendor Product Version
dnsmasq dnsmasq Version: 0   < 2.92rel2
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 5.3,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-4891",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-11T18:27:33.459839Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-11T18:27:36.545Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:10.2"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 10",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "0:2.90-7.el10_2",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:8"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 8",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "0:2.79-36.el8_10",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:9"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 9",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "0:2.85-18.el9_8.1",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:rhel_eus:9.6"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 9.6 Extended Update Support",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "0:2.85-17.el9_6.1",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/a:redhat:openshift:4.19::el9"
            ],
            "defaultStatus": "affected",
            "packageName": "rhcos",
            "product": "Red Hat OpenShift Container Platform 4.19",
            "vendor": "Red Hat",
            "versions": [
              {
                "lessThan": "*",
                "status": "unaffected",
                "version": "4.19.9.6.202607151909-0",
                "versionType": "rpm"
              }
            ]
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:6"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 6",
            "vendor": "Red Hat"
          },
          {
            "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:7"
            ],
            "defaultStatus": "affected",
            "packageName": "dnsmasq",
            "product": "Red Hat Enterprise Linux 7",
            "vendor": "Red Hat"
          }
        ],
        "datePublic": "2026-05-09T00:00:00.000Z",
        "descriptions": [
          {
            "lang": "en",
            "value": "A heap out-of-bounds read vulnerability was discovered in dnsmasq\u0027s DNSSEC validation. When processing RRSIG records, dnsmasq calculates the signature length by subtracting the fixed field size from the record\u0027s 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."
          }
        ],
        "metrics": [
          {
            "other": {
              "content": {
                "namespace": "https://access.redhat.com/security/updates/classification/",
                "value": "Important"
              },
              "type": "Red Hat severity rating"
            }
          },
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            },
            "format": "CVSS"
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-125",
                "description": "Out-of-bounds Read",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-25T12:05:48.869Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-4891"
          },
          {
            "name": "RHBZ#2458517",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2458517"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4891.json"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:40762"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19158"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:20589"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:34508"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19373"
          }
        ],
        "solutions": [
          {
            "lang": "en",
            "value": "RHSA-2026:40762: Red Hat OpenShift Container Platform 4.19"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19158: Red Hat Enterprise Linux AppStream (v. 10)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:20589: Red Hat Enterprise Linux AppStream (v. 8)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:34508: Red Hat Enterprise Linux AppStream EUS (v.9.6)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19373: Red Hat Enterprise Linux AppStream (v. 9)"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2026-04-14T22:39:35.826Z",
            "value": "Reported to Red Hat."
          },
          {
            "lang": "en",
            "time": "2026-05-09T00:00:00.000Z",
            "value": "Made public."
          }
        ],
        "title": "dnsmasq: RRSIG rdlen underflow leading to heap OOB read",
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "dnsmasq",
          "vendor": "dnsmasq",
          "versions": [
            {
              "lessThan": "2.92rel2",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-125: Out-of-bounds Read",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-20T14:08:50.799Z",
        "orgId": "37e5125f-f79b-445b-8fad-9564f167944b",
        "shortName": "certcc"
      },
      "references": [
        {
          "url": "https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html"
        },
        {
          "url": "https://www.kb.cert.org/vuls/id/471747"
        },
        {
          "url": "https://thekelleys.org.uk/dnsmasq/CVE/"
        },
        {
          "url": "https://github.com/NixOS/nixpkgs/pull/519082"
        },
        {
          "url": "https://github.com/NixOS/nixpkgs/pull/519093"
        },
        {
          "url": "https://github.com/pi-hole/FTL/releases/tag/v6.6.2"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "CVE-2026-4891",
      "x_generator": {
        "engine": "VINCE 3.0.41",
        "env": "prod",
        "origin": "https://cveawg.mitre.org/api/cve/CVE-2026-4891"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b",
    "assignerShortName": "certcc",
    "cveId": "CVE-2026-4891",
    "datePublished": "2026-05-11T16:47:33.202Z",
    "dateReserved": "2026-03-26T13:07:05.406Z",
    "dateUpdated": "2026-08-25T12:05:48.869Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"dnsmasq: RRSIG rdlen underflow leading to heap OOB read\", \"metrics\": [{\"other\": {\"type\": \"Red Hat severity rating\", \"content\": {\"value\": \"Important\", \"namespace\": \"https://access.redhat.com/security/updates/classification/\"}}}, {\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}}], \"affected\": [{\"cpes\": [\"cpe:/o:redhat:enterprise_linux:10.2\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 10\", \"versions\": [{\"status\": \"unaffected\", \"version\": \"0:2.90-7.el10_2\", \"lessThan\": \"*\", \"versionType\": \"rpm\"}], \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/a:redhat:enterprise_linux:8\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 8\", \"versions\": [{\"status\": \"unaffected\", \"version\": \"0:2.79-36.el8_10\", \"lessThan\": \"*\", \"versionType\": \"rpm\"}], \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/a:redhat:enterprise_linux:9\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 9\", \"versions\": [{\"status\": \"unaffected\", \"version\": \"0:2.85-18.el9_8.1\", \"lessThan\": \"*\", \"versionType\": \"rpm\"}], \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/a:redhat:rhel_eus:9.6\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 9.6 Extended Update Support\", \"versions\": [{\"status\": \"unaffected\", \"version\": \"0:2.85-17.el9_6.1\", \"lessThan\": \"*\", \"versionType\": \"rpm\"}], \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/a:redhat:openshift:4.19::el9\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat OpenShift Container Platform 4.19\", \"versions\": [{\"status\": \"unaffected\", \"version\": \"4.19.9.6.202607151909-0\", \"lessThan\": \"*\", \"versionType\": \"rpm\"}], \"packageName\": \"rhcos\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/o:redhat:enterprise_linux:6\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 6\", \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}, {\"cpes\": [\"cpe:/o:redhat:enterprise_linux:7\"], \"vendor\": \"Red Hat\", \"product\": \"Red Hat Enterprise Linux 7\", \"packageName\": \"dnsmasq\", \"collectionURL\": \"https://access.redhat.com/downloads/content/package-browser/\", \"defaultStatus\": \"affected\"}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-04-14T22:39:35.826Z\", \"value\": \"Reported to Red Hat.\"}, {\"lang\": \"en\", \"time\": \"2026-05-09T00:00:00.000Z\", \"value\": \"Made public.\"}], \"solutions\": [{\"lang\": \"en\", \"value\": \"RHSA-2026:40762: Red Hat OpenShift Container Platform 4.19\"}, {\"lang\": \"en\", \"value\": \"RHSA-2026:19158: Red Hat Enterprise Linux AppStream (v. 10)\"}, {\"lang\": \"en\", \"value\": \"RHSA-2026:20589: Red Hat Enterprise Linux AppStream (v. 8)\"}, {\"lang\": \"en\", \"value\": \"RHSA-2026:34508: Red Hat Enterprise Linux AppStream EUS (v.9.6)\"}, {\"lang\": \"en\", \"value\": \"RHSA-2026:19373: Red Hat Enterprise Linux AppStream (v. 9)\"}], \"x_adpType\": \"supplier\", \"datePublic\": \"2026-05-09T00:00:00.000Z\", \"references\": [{\"url\": \"https://access.redhat.com/security/cve/CVE-2026-4891\", \"tags\": [\"vdb-entry\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://bugzilla.redhat.com/show_bug.cgi?id=2458517\", \"name\": \"RHBZ#2458517\", \"tags\": [\"issue-tracking\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4891.json\", \"tags\": [\"x_sadp-csaf-vex\"]}, {\"url\": \"https://access.redhat.com/errata/RHSA-2026:40762\", \"tags\": [\"vendor-advisory\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://access.redhat.com/errata/RHSA-2026:19158\", \"tags\": [\"vendor-advisory\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://access.redhat.com/errata/RHSA-2026:20589\", \"tags\": [\"vendor-advisory\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://access.redhat.com/errata/RHSA-2026:34508\", \"tags\": [\"vendor-advisory\", \"x_refsource_REDHAT\"]}, {\"url\": \"https://access.redhat.com/errata/RHSA-2026:19373\", \"tags\": [\"vendor-advisory\", \"x_refsource_REDHAT\"]}], \"x_generator\": {\"engine\": \"sadp-cli 1.0.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"A heap out-of-bounds read vulnerability was discovered in dnsmasq\u0027s DNSSEC validation. When processing RRSIG records, dnsmasq calculates the signature length by subtracting the fixed field size from the record\u0027s 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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-125\", \"description\": \"Out-of-bounds Read\"}]}], \"providerMetadata\": {\"orgId\": \"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\", \"shortName\": \"redhat-SADP\", \"dateUpdated\": \"2026-08-25T12:05:48.869Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"LOW\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-4891\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-11T18:27:33.459839Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-11T18:27:24.527Z\"}}], \"cna\": {\"title\": \"CVE-2026-4891\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"affected\": [{\"vendor\": \"dnsmasq\", \"product\": \"dnsmasq\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"2.92rel2\", \"versionType\": \"custom\"}]}], \"references\": [{\"url\": \"https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html\"}, {\"url\": \"https://www.kb.cert.org/vuls/id/471747\"}, {\"url\": \"https://thekelleys.org.uk/dnsmasq/CVE/\"}, {\"url\": \"https://github.com/NixOS/nixpkgs/pull/519082\"}, {\"url\": \"https://github.com/NixOS/nixpkgs/pull/519093\"}, {\"url\": \"https://github.com/pi-hole/FTL/releases/tag/v6.6.2\"}], \"x_generator\": {\"env\": \"prod\", \"engine\": \"VINCE 3.0.41\", \"origin\": \"https://cveawg.mitre.org/api/cve/CVE-2026-4891\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"description\": \"CWE-125: Out-of-bounds Read\"}]}], \"providerMetadata\": {\"orgId\": \"37e5125f-f79b-445b-8fad-9564f167944b\", \"shortName\": \"certcc\", \"dateUpdated\": \"2026-05-20T14:08:50.799Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-4891\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-25T12:05:48.869Z\", \"dateReserved\": \"2026-03-26T13:07:05.406Z\", \"assignerOrgId\": \"37e5125f-f79b-445b-8fad-9564f167944b\", \"datePublished\": \"2026-05-11T16:47:33.202Z\", \"assignerShortName\": \"certcc\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.