CVE-2026-69186

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{"affected": [{"affectedData": [{"product": "c-ares", "vendor": "c-ares", "versions": [{"status": "affected", "version": "< 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": "2026-09-23T18:12:04.247", "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"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-69186", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-18T19:50:58.245833Z", "version": "2.0.3"}}]}, "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"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "c-ares: c-ares: Denial of Service via unvalidated DNS header record counts", "id": "2538212", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2538212"}, "csaw": false, "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": "draft"}, "cwe": "CWE-1284", "details": ["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.", "A flaw was found in c-ares, an asynchronous resolver library. A remote attacker can send a specially crafted DNS response that causes the `ares_dns_parse()` function to trust attacker-controlled record counts without validating if the response contains enough bytes for the claimed records. This can lead to disproportionate heap memory reservation, resulting in a memory-amplification denial of service (DoS) by degrading or denying name resolution."], "name": "CVE-2026-69186", "package_state": [{"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-09-18T17:25:42Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-69186\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-69186\nhttps://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4\nhttps://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab\nhttps://github.com/c-ares/c-ares/pull/1134\nhttps://github.com/c-ares/c-ares/releases/tag/v1.34.7\nhttps://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.34.7)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "c-ares", "source": "cna", "vendor": "c-ares"}, "product": "c-ares", "vendor": "c-ares"}], "created": "2026-09-19T12:15:17.524039+00:00", "updated": "2026-09-23T02:00:10.862794+00:00", "vendors": ["c-ares", "c-ares$PRODUCT$c-ares"]}