CVE-2026-93250: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xj6p-hw9r-5g4r",
  "modified" : "2026-09-25T06:30:28Z",
  "published" : "2026-09-24T18:31:24Z",
  "aliases" : [ "CVE-2026-93250" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: mdb: Fix use-after-free in vxlan_mdb_flush()\n\nvxlan_mdb_flush() iterates over the MDB entries using\nhlist_for_each_entry_safe(), which only tolerates the removal of the\ncurrent entry. Contrary to the comment above the loop, the removal of an\nentry can trigger the removal of another entry.\n\nFlushing the remotes of a (*, G) entry also removes the (S, G) entries\nthat were created for its source list, once they are left without\nremotes:\n\nvxlan_mdb_remotes_flush()\n-> vxlan_mdb_remote_del()\n   -> vxlan_mdb_remote_srcs_del()\n      -> vxlan_mdb_remote_src_del()\n         -> vxlan_mdb_remote_src_fwd_del()\n            -> __vxlan_mdb_del()\n               -> vxlan_mdb_entry_put()\n\nSuch an entry can be located after the (*, G) entry in the list, as\nvxlan_mdb_entry_get() returns an existing entry without moving it to the\nhead of the list. This order is obtained by adding the (S, G) entry\nbefore the (*, G) entry, the latter with NLM_F_REPLACE, as the addition\nof the source otherwise fails with -EEXIST. The (S, G) entry is then the\nentry saved by hlist_for_each_entry_safe() and it is freed while the\n(*, G) entry is processed. The next iteration calls hlist_del() on it\nagain, writing LIST_POISON1 to LIST_POISON2 [1].\n\nBesides device deletion, the flush is also reachable from RTM_DELMDB\nwith NLM_F_BULK.\n\nFix by re-reading the next entry after the remotes were flushed. The\ncurrent entry cannot be removed by this flush, as source lists can only\nbe configured on (*, G) entries and the removed entries are (S, G)\nentries. It is therefore still linked and its next pointer reflects the\nremovals.\n\n[1]\nBUG: KASAN: wild-memory-access in vxlan_mdb_entry_put.part.0+0x328/0x588\nWrite of size 8 at addr dead000000000122 by task ip/327\n\nCPU: 3 UID: 1000 PID: 327 Comm: ip Not tainted 7.2.0-rc7 #2 PREEMPT\nCall trace:\n vxlan_mdb_entry_put.part.0+0x328/0x588\n vxlan_mdb_flush+0x1d8/0x25c\n vxlan_mdb_fini+0x8c/0x100\n vxlan_uninit+0x1c/0x7c\n unregister_netdevice_many_notify+0x954/0xd4c\n rtnl_dellink+0x210/0x530\n rtnetlink_rcv_msg+0x434/0x4d0\n netlink_rcv_skb+0xc4/0x204\n rtnetlink_rcv+0x18/0x24\n netlink_unicast+0x4b8/0x548\n netlink_sendmsg+0x29c/0x560\n ____sys_sendmsg+0x390/0x3ec\n ___sys_sendmsg+0x114/0x188\n __sys_sendmsg+0xf0/0x178\n __arm64_sys_sendmsg+0x48/0x60\n invoke_syscall.constprop.0+0x58/0x180\n el0_svc_common.constprop.0+0x74/0x140\n do_el0_svc+0x30/0x40\n el0_svc+0x38/0x98\n el0t_64_sync_handler+0xa0/0xe4\n el0t_64_sync+0x198/0x19c",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-93250"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/3e6b705bc162fc7257645725a7d2cf6c71250318"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/bc2dc66a6693a78f8c1e6ca2dbebd50f16e2c366"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/c7dc26d06f90ca11bbd6114f6a62a67d038816c7"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/f26400b325bdc2868e40612c4804c82cf8ba6275"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/f8a9b988e7a7bc674e74e8c901794d792c35689e"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-24T16:17:21Z"
  }
}