{"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":"2026-09-14T12:00:47.221Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:00:47.221Z"},"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":[{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"159a4fab7170badd6c4a553aef81cac079d6f4ee","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"b3526ae3351968f6726bcbe25d8d09973ad79109","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"7f5bcdc8da15077ebe846c2756a5a17741021410","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"89c8e0733e8c46b7973503f15b1b31a8587d8030","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"f15b87521168c2a92cb1931f532cba422f856f01","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"edeefb111d6181a4aa278f415b005efe284b9489","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"3f019571928b269feebcff59926ec13294215e0e","status":"affected","versionType":"git"},{"version":"030d794bf49855f5e2a9e8dfbfad34211d1eb08b","lessThan":"5ce1ed6159731a41fdd0b03eedbed4e147036a5a","status":"affected","versionType":"git"}]},{"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-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.10","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/159a4fab7170badd6c4a553aef81cac079d6f4ee"},{"url":"https://git.kernel.org/stable/c/b3526ae3351968f6726bcbe25d8d09973ad79109"},{"url":"https://git.kernel.org/stable/c/7f5bcdc8da15077ebe846c2756a5a17741021410"},{"url":"https://git.kernel.org/stable/c/89c8e0733e8c46b7973503f15b1b31a8587d8030"},{"url":"https://git.kernel.org/stable/c/f15b87521168c2a92cb1931f532cba422f856f01"},{"url":"https://git.kernel.org/stable/c/edeefb111d6181a4aa278f415b005efe284b9489"},{"url":"https://git.kernel.org/stable/c/3f019571928b269feebcff59926ec13294215e0e"},{"url":"https://git.kernel.org/stable/c/5ce1ed6159731a41fdd0b03eedbed4e147036a5a"}],"title":"sunrpc: init gssp_lock before publishing proc entry","x_generator":{"engine":"bippy-1.2.0"}}}}