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        "cveId": "CVE-2026-78227",
        "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "state": "PUBLISHED",
        "assignerShortName": "NLnet Labs",
        "dateReserved": "2026-09-07T14:06:21.963Z",
        "datePublished": "2026-09-16T08:29:52.342Z",
        "dateUpdated": "2026-09-16T15:33:54.267Z"
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    "containers": {
        "cna": {
            "title": "Use-after-free in DoQ stream output buffer on reset re-transmission",
            "datePublic": "2026-09-16T00:00:00.000Z",
            "affected": [
                {
                    "vendor": "NLnet Labs",
                    "product": "Unbound",
                    "versions": [
                        {
                            "version": "1.22.0",
                            "status": "affected",
                            "lessThan": "1.26.1",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
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            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "NLnet Labs Unbound 1.22.0 up to and including 1.26.1, has a use-after-free vulnerability when compiled for DNS-over-QUIC support with '--with-libngtcp2'. Each DoQ stream owns an output buffer that holds the DNS response. ngtcp2's retransmission buffer keeps a shallow pointer into the output buffer for as long as a STREAM frame may be resent. On a client RESET_STREAM, the output buffer is freed but ngtcp2 still holds the matching retransmission entries. The next PTO timeout makes ngtcp2 re-encode the STREAM frame and copy from the freed buffer. A malicious actor that can query Unbound over DoQ and that withholds ACKs, sends RESET_STREAM, and waits for PTO, reaches this use-after-free with no privilege. This leads to retransmissions against freed memory and eventually an abnormal server exit under a 20-query spray."
                }
            ],
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                            "lang": "en",
                            "value": "compiled with DNS-over-QUIC support"
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                        "version": "3.1",
                        "baseScore": 6.5,
                        "baseSeverity": "MEDIUM",
                        "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L"
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                            "cweId": "CWE-416",
                            "description": "CWE-416: Use After Free",
                            "type": "CWE"
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                    ]
                }
            ],
            "solutions": [
                {
                    "lang": "en",
                    "value": "This issue is fixed starting with version 1.26.1"
                }
            ],
            "timeline": [
                {
                    "time": "2026-08-11T00:00:00.000Z",
                    "lang": "en",
                    "value": "Issue reported by Yuqi Qiu"
                },
                {
                    "time": "2026-08-13T00:00:00.000Z",
                    "lang": "en",
                    "value": "NLnet Labs shares patch"
                },
                {
                    "time": "2026-08-14T00:00:00.000Z",
                    "lang": "en",
                    "value": "Yuqi Qiu verifies patch"
                },
                {
                    "time": "2026-09-16T00:00:00.000Z",
                    "lang": "en",
                    "value": "Fixes released with version 1.26.1"
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            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Yuqi Qiu (Nankai University, AOSP Lab)",
                    "type": "finder"
                },
                {
                    "lang": "en",
                    "value": "Xiang Li (Nankai University, AOSP Lab)",
                    "type": "finder"
                }
            ],
            "references": [
                {
                    "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-78227.txt",
                    "tags": [
                        "vendor-advisory"
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
                "shortName": "NLnet Labs",
                "dateUpdated": "2026-09-16T08:29:52.342Z"
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                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-09-16T15:33:40.171223Z",
                                "id": "CVE-2026-78227",
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                "title": "CISA ADP Vulnrichment",
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