{
  "threat_severity" : "Moderate",
  "public_date" : "2026-04-03T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd",
    "id" : "2454874",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2454874"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-825",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nNFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd\nThe /proc/fs/nfs/exports proc entry is created at module init\nand persists for the module's lifetime. exports_proc_open()\ncaptures the caller's current network namespace and stores\nits svc_export_cache in seq->private, but takes no reference\non the namespace. If the namespace is subsequently torn down\n(e.g. container destruction after the opener does setns() to a\ndifferent namespace), nfsd_net_exit() calls nfsd_export_shutdown()\nwhich frees the cache. Subsequent reads on the still-open fd\ndereference the freed cache_detail, walking a freed hash table.\nHold a reference on the struct net for the lifetime of the open\nfile descriptor. This prevents nfsd_net_exit() from running --\nand thus prevents nfsd_export_shutdown() from freeing the cache\n-- while any exports fd is open. cache_detail already stores\nits net pointer (cd->net, set by cache_create_net()), so\nexports_release() can retrieve it without additional per-file\nstorage.", "A flaw was found in the Linux kernel's Network File System Daemon (NFSD) component. A local user can exploit this vulnerability by opening the `/proc/fs/nfs/exports` file and then causing the associated network namespace to be destroyed. Subsequent attempts to read from the still-open file descriptor will lead to dereferencing freed memory, which can result in a system crash or a Denial of Service (DoS)." ],
  "statement" : "`exports_proc_open()` cached export cache without pinning `struct net`. After namespace teardown, `nfsd_export_shutdown()` freed the cache while the fd remained open. Holding a net reference for the fd lifetime prevents the UAF. Relevant to NFS server and container or namespace workflows.",
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-31403\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31403\nhttps://lore.kernel.org/linux-cve-announce/2026040328-CVE-2026-31403-5446@gregkh/T" ],
  "name" : "CVE-2026-31403",
  "csaw" : false
}