{
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    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-53921",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-06-11T15:46:12.316Z",
        "datePublished": "2026-10-23T13:20:30.249Z",
        "dateUpdated": "2026-10-29T13:28:11.455Z"
    },
    "containers": {
        "cna": {
            "title": "odhcpd: Stack buffer overflow in DHCPv6 IA reply serialization (2 independent sites)",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-121",
                            "lang": "en",
                            "description": "CWE-121: Stack-based Buffer Overflow",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "NETWORK",
                        "availabilityImpact": "HIGH",
                        "baseScore": 9.8,
                        "baseSeverity": "CRITICAL",
                        "confidentialityImpact": "HIGH",
                        "integrityImpact": "HIGH",
                        "privilegesRequired": "NONE",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                        "version": "3.1"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc03",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc03"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35f3",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35f3"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819a9",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819a9"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b5a",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b5a"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7b7",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7b7"
                },
                {
                    "name": "https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade28328",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade28328"
                }
            ],
            "affected": [
                {
                    "vendor": "openwrt",
                    "product": "odhcpd",
                    "versions": [
                        {
                            "version": "< 25.12",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-10-23T13:20:30.249Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler writes past the end of a fixed 512-byte stack buffer (pdbuf) when a single DHCPv6 REQUEST carries enough IA options to nearly exhaust the reply space. Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic. This issue has been patched in version 25.12."
                }
            ],
            "source": {
                "advisory": "GHSA-7fwx-hhrg-3496",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "references": [
                    {
                        "url": "https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496",
                        "tags": [
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                ],
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-10-29T13:27:12.914498Z",
                                "id": "CVE-2026-53921",
                                "options": [
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                                        "Exploitation": "poc"
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                                        "Technical Impact": "total"
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                                "role": "CISA Coordinator",
                                "version": "2.0.3"
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                "title": "CISA ADP Vulnrichment",
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}