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CVE-2026-69186 (GCVE-0-2026-69186)

Vulnerability from cvelistv5 – Published: 2026-09-18 17:25 – Updated: 2026-09-18 17:25
VLAI
Title
c-ares: Memory-amplification denial of service via unvalidated DNS header record counts
Summary
c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE
  • CWE-400 - Uncontrolled Resource Consumption
Assigner
References
Impacted products
Vendor Product Version CPE status
c-ares c-ares Affected: < 1.34.7
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "c-ares",
          "vendor": "c-ares",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.34.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "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:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:25:42.440Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj"
        },
        {
          "name": "https://github.com/c-ares/c-ares/pull/1134",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/c-ares/c-ares/pull/1134"
        },
        {
          "name": "https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4"
        },
        {
          "name": "https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"
        },
        {
          "name": "https://github.com/c-ares/c-ares/releases/tag/v1.34.7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/c-ares/c-ares/releases/tag/v1.34.7"
        }
      ],
      "source": {
        "advisory": "GHSA-jv8r-gqr9-68wj",
        "discovery": "UNKNOWN"
      },
      "title": "c-ares: Memory-amplification denial of service via unvalidated DNS header record counts"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-69186",
    "datePublished": "2026-09-18T17:25:42.440Z",
    "dateReserved": "2026-08-03T16:00:23.482Z",
    "dateUpdated": "2026-09-18T17:25:42.440Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "c-ares",
                "vendor": "c-ares",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 1.34.7"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7."
          }
        ],
        "id": "CVE-2026-69186",
        "lastModified": "2026-09-18T18:17:11.637",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 5.3,
                "baseSeverity": "MEDIUM",
                "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:L",
                "version": "3.1"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 1.4,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-09-18T18:17:11.637",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/c-ares/c-ares/pull/1134"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/c-ares/c-ares/releases/tag/v1.34.7"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-400"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-18T00:29:30Z",
      "cve": "CVE-2026-69186",
      "id": "CVE-2026-69186",
      "initial_release_date": "2026-08-25T01:22:40Z",
      "product_status:known_affected": "430",
      "product_status:recommended": "55",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-69186",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-69186.json",
      "version": "10"
    }
  }
}



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