{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-89540",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-11T19:38:34.721Z",
        "datePublished": "2026-09-11T19:44:17.440Z",
        "dateUpdated": "2026-10-19T08:48:31.930Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-19T08:48:31.930Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: init gssp_lock before publishing proc entry\n\ncreate_use_gss_proxy_proc_entry() publishes /proc/net/rpc/use-gss-proxy\nvia proc_create_data() before init_gssp_clnt() runs mutex_init() on\nsn->gssp_lock.  Once the dentry is linked under proc_subdir_lock it is\nimmediately reachable from userspace, so a write that lands in the\nwindow drives set_gssp_clnt() into mutex_lock() on a zero-initialized\nstruct mutex.\n\n    create_use_gss_proxy_proc_entry(net)\n      proc_create_data(\"use-gss-proxy\", ...)   /* dentry live */\n      init_gssp_clnt(sn)\n        mutex_init(&sn->gssp_lock)             /* too late */\n\n    write_gssp()\n      set_gssp_clnt(net)\n        mutex_lock(&sn->gssp_lock)             /* uninitialized */\n        gssp_rpc_create(...)\n        sn->gssp_clnt = clnt\n        mutex_unlock(&sn->gssp_lock)\n\nThe window spans only the two statements between proc_create_data()\nreturning and init_gssp_clnt(), so a writer reaches it only if the\nregistering thread is preempted there while another task is already\nopening the freshly published file.  register_pernet_subsys() runs in\npreemptible context under pernet_ops_rwsem, so that preemption is\npossible, and the window widens on auth_rpcgss module load, when the\nproc entry is created for every live net namespace whose tasks are\nalready running.  A writer that wins the race locks a zero-filled\nstruct mutex.  On CONFIG_DEBUG_MUTEXES the missing magic value trips a\n\"lock used without init\" splat; on a production kernel the fast path\nacquires the lock via CMPXCHG(owner, 0, current).  In the latter case\na second writer that arrives before init_gssp_clnt() re-zeroes owner\ncan enter set_gssp_clnt() concurrently, shut down the first writer's\nclnt while it is still in use, and leak the loser's clnt.\n\nFix by initializing sn->gssp_lock in sunrpc_init_net() so its lifetime\nmatches the sunrpc_net it lives in.  sn->gssp_clnt is already NULL from\nthe kzalloc that backs net_generic storage, so the lazy helper is no\nlonger needed; drop init_gssp_clnt(), its prototype, and the call from\ncreate_use_gss_proxy_proc_entry().  sunrpc.ko is a build-time\ndependency of auth_rpcgss.ko, so sunrpc_init_net() has always run on\nevery netns before any auth_gss pernet init can publish the proc\nentry."
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                        "baseScore": 7.8,
                        "baseSeverity": "HIGH"
                    },
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "AV:L - The bug is reached only by write(2) to /proc/net/rpc/use-gss-proxy (write_gssp → set_gssp_clnt → mutex_lock(&sn->gssp_lock)); remote NFS/RPC peers never hit that procfs path.\nAC:L - The attacker fully controls writer threads that hammer the proc file, and on auth_rpcgss module load register_pernet_subsys() publishes it for every live netns whose tasks are already running; preemption between proc_create_data() and mutex_init() is possible in that preemptible pernet context, so the race is attacker-driven.\nPR:L - The 0600 use-gss-proxy entry inherits /proc/net ownership from proc_net_ns_init()'s make_kuid(net->user_ns, 0), so an unprivileged user who unshares user+net namespaces owns the file; write_gssp() has no capable() check.\nUI:N - The attacker creates the namespace and writes \"1\" to the proc file from their own tasks; no victim must mount a filesystem, open a file, or otherwise cooperate.\nS:U - Uninitialized-mutex use and concurrent rpc_clnt teardown corrupt host kernel memory inside the same kernel security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - A writer that wins the race locks a zeroed mutex; mutex_init() can then re-zero owner so a second writer enters set_gssp_clnt() concurrently and rpc_shutdown_client()s a live rpc_clnt, a use-after-free that per kernel guidance yields an arbitrary read primitive.\nI:H - Concurrent set_gssp_clnt() can shut down an in-use rpc_clnt (UAF) while mutex_init() of a held lock corrupts mutex wait-list state, giving heap/lock-structure writes exploitable for control-flow hijack rather than a pure crash.\nA:H - CONFIG_DEBUG_MUTEXES treats the uninitialized lock as a lock-used-without-init splat/oops, and on production kernels the rpc_clnt UAF and corrupted mutex wait lists cause a kernel oops or panic."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sunrpc/auth_gss/gss_rpc_upcall.c",
                        "net/sunrpc/auth_gss/gss_rpc_upcall.h",
                        "net/sunrpc/auth_gss/svcauth_gss.c",
                        "net/sunrpc/sunrpc_syms.c"
                    ],
                    "versions": [
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                            "version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
                            "lessThan": "159a4fab7170badd6c4a553aef81cac079d6f4ee",
                            "status": "affected",
                            "versionType": "git"
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                            "lessThan": "b3526ae3351968f6726bcbe25d8d09973ad79109",
                            "status": "affected",
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                            "status": "affected",
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                            "lessThan": "89c8e0733e8c46b7973503f15b1b31a8587d8030",
                            "status": "affected",
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                        {
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                            "lessThan": "f15b87521168c2a92cb1931f532cba422f856f01",
                            "status": "affected",
                            "versionType": "git"
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                        {
                            "version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
                            "lessThan": "edeefb111d6181a4aa278f415b005efe284b9489",
                            "status": "affected",
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                            "version": "030d794bf49855f5e2a9e8dfbfad34211d1eb08b",
                            "lessThan": "3f019571928b269feebcff59926ec13294215e0e",
                            "status": "affected",
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                            "status": "affected",
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                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sunrpc/auth_gss/gss_rpc_upcall.c",
                        "net/sunrpc/auth_gss/gss_rpc_upcall.h",
                        "net/sunrpc/auth_gss/svcauth_gss.c",
                        "net/sunrpc/sunrpc_syms.c"
                    ],
                    "versions": [
                        {
                            "version": "3.10",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "3.10",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.270",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.221",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.188",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.157",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.109",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.50",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.4",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
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                            "operator": "OR",
                            "negate": false,
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                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                                    "versionEndExcluding": "5.10.270"
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                                    "vulnerable": true,
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            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/159a4fab7170badd6c4a553aef81cac079d6f4ee"
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                },
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                },
                {
                    "url": "https://git.kernel.org/stable/c/5ce1ed6159731a41fdd0b03eedbed4e147036a5a"
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            ],
            "title": "sunrpc: init gssp_lock before publishing proc entry",
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        "adp": [
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                            "content": {
                                "id": "CVE-2026-89540",
                                "role": "CISA Coordinator",
                                "options": [
                                    {
                                        "Exploitation": "none"
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                                "version": "2.0.3",
                                "timestamp": "2026-10-16T19:23:23.496498Z"
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}