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    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2025-5994",
        "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "state": "PUBLISHED",
        "assignerShortName": "NLnet Labs",
        "dateReserved": "2025-06-11T09:08:05.767Z",
        "datePublished": "2025-07-16T14:38:22.738Z",
        "dateUpdated": "2025-11-03T18:13:56.352Z"
    },
    "containers": {
        "cna": {
            "title": "Cache poisoning via the ECS-enabled Rebirthday Attack",
            "datePublic": "2025-07-16T00:00:00.000Z",
            "affected": [
                {
                    "vendor": "NLnet Labs",
                    "product": "Unbound",
                    "versions": [
                        {
                            "version": "1.6.2",
                            "status": "affected",
                            "lessThan": "1.23.0",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies."
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "Compiled and configured for ECS support"
                        }
                    ],
                    "cvssV4_0": {
                        "version": "4.0",
                        "baseScore": 8.7,
                        "baseSeverity": "HIGH",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/R:U/V:C"
                    }
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-349",
                            "description": "CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "solutions": [
                {
                    "lang": "en",
                    "value": "This issue is fixed in 1.23.1 and all later versions. Not using EDNS Client Subnet (ECS) is also a mitigation for affected versions."
                }
            ],
            "timeline": [
                {
                    "time": "2025-01-02T00:00:00.000Z",
                    "lang": "en",
                    "value": "Issue reported by Xiang Li"
                },
                {
                    "time": "2025-01-03T00:00:00.000Z",
                    "lang": "en",
                    "value": "Issue acknowledged by NLnet Labs"
                },
                {
                    "time": "2025-01-08T00:00:00.000Z",
                    "lang": "en",
                    "value": "Mitigation shared with Xiang Li"
                },
                {
                    "time": "2025-07-16T00:00:00.000Z",
                    "lang": "en",
                    "value": "Fix released with Unbound 1.23.1 (coordinated with other vendors)"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Xiang Li (AOSP Lab, Nankai University)",
                    "type": "finder"
                }
            ],
            "references": [
                {
                    "url": "https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt",
                    "tags": [
                        "vendor-advisory"
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
                "shortName": "NLnet Labs",
                "dateUpdated": "2025-07-16T14:38:22.738Z"
            }
        },
        "adp": [
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                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2025-07-16T15:42:14.147972Z",
                                "id": "CVE-2025-5994",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
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                                        "Technical Impact": "partial"
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                                "role": "CISA Coordinator",
                                "version": "2.0.3"
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                "title": "CISA ADP Vulnrichment",
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                    "dateUpdated": "2025-07-16T15:42:18.657Z"
                }
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            {
                "title": "CVE Program Container",
                "references": [
                    {
                        "url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00019.html"
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                    "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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