net: nexthop: fix percpu use-after-free in remove_nh_grp_entry_CVE-2026-43374

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: nexthop: fix percpu use-after-free in remove_nh_grp_entry\n\nWhen removing a nexthop from a group, remove_nh_grp_entry() publishes\nthe new group via rcu_assign_pointer() then immediately frees the\nremoved entry's percpu stats with free_percpu(). However, the\nsynchronize_net() grace period in the caller remove_nexthop_from_groups()\nruns after the free. RCU readers that entered before the publish still\nsee the old group and can dereference the freed stats via\nnh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a\nuse-after-free on percpu memory.\n\nFix by deferring the free_percpu() until after synchronize_net() in the\ncaller. Removed entries are chained via nh_list onto a local deferred\nfree list. After the grace period completes and all RCU readers have\nfinished, the percpu stats are safely freed.",
    "published": "2026-05-08T14:21:24.537Z",
    "modified": "2026-05-11T06:33:53.303Z",
    "type": "cve",
    "title": "net: nexthop: fix percpu use-after-free in remove_nh_grp_entry",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/abf4feaee6405f1441929c6ebe7a250f2cd170a7\nhttps://git.kernel.org/stable/c/ab5ebab9664214ba41a7633cb4e72f128204f924\nhttps://git.kernel.org/stable/c/9e08ad731862b22a87cc55f752e16d66cdc9e231\nhttps://git.kernel.org/stable/c/b2662e7593e94ae09b1cf7ee5f09160a3612bcb2",
    "id": "CVE-2026-43374",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux f4676ea74b8549cd88dbfe2a592ce4530039e61f\nLinux Linux f4676ea74b8549cd88dbfe2a592ce4530039e61f\nLinux Linux f4676ea74b8549cd88dbfe2a592ce4530039e61f\nLinux Linux f4676ea74b8549cd88dbfe2a592ce4530039e61f\nLinux Linux 6.9",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
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            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "f4676ea74b8549cd88dbfe2a592ce4530039e61f",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
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    "ai_version": "",
    "ai_score": 0
}