CVE-2026-68386 (GCVE-0-2026-68386)
Vulnerability from cvelistv5
Published
2026-08-10 12:04
Modified
2026-08-19 16:34
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Reject unhashed UDP sockets on sockmap update UDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means sk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false. Because sockmap accepts unbound UDP sockets, a BPF program can increment a socket's refcount via lookup. If the socket is subsequently bound, the transition from unbound to bound causes bpf_sk_release() to skip the decrement of the refcount, causing a memory leak. unreferenced object 0xffff88810bc2eb40 (size 1984): comm "test_progs", pid 2451, jiffies 4295320596 hex dump (first 32 bytes): 7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00 ................ 02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace (crc bdee079d): kmem_cache_alloc_noprof+0x557/0x660 sk_prot_alloc+0x69/0x240 sk_alloc+0x30/0x460 inet_create+0x2ce/0xf80 __sock_create+0x25b/0x5c0 __sys_socket+0x119/0x1d0 __x64_sys_socket+0x72/0xd0 do_syscall_64+0xa1/0x5f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Instead of special-casing for refcounted sockets, reject unhashed UDP sockets during sockmap updates, as there is no benefit to supporting those. This effectively reverts the commit under Fixes, with two exceptions: 1. sock_map_sk_state_allowed() maintains a fall-through `return true`. 2. In the spirit of commit b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage"), the proto::unhash BPF handler is not reintroduced. Historical note: this issue is related to commit 67312adc96b5 ("bpf: reject unhashed sockets in bpf_sk_assign").
References
Impacted products
Vendor Product Version
Linux Linux Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
Version: 0c48eefae712c2fd91480346a07a1a9cd0f9470b
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/sock_map.c"
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              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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              "negate": false,
              "operator": "OR"
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          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject unhashed UDP sockets on sockmap update\n\nUDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means\nsk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false.\n\nBecause sockmap accepts unbound UDP sockets, a BPF program can increment a\nsocket\u0027s refcount via lookup. If the socket is subsequently bound, the\ntransition from unbound to bound causes bpf_sk_release() to skip the\ndecrement of the refcount, causing a memory leak.\n\nunreferenced object 0xffff88810bc2eb40 (size 1984):\n  comm \"test_progs\", pid 2451, jiffies 4295320596\n  hex dump (first 32 bytes):\n    7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00  ................\n    02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............\n  backtrace (crc bdee079d):\n    kmem_cache_alloc_noprof+0x557/0x660\n    sk_prot_alloc+0x69/0x240\n    sk_alloc+0x30/0x460\n    inet_create+0x2ce/0xf80\n    __sock_create+0x25b/0x5c0\n    __sys_socket+0x119/0x1d0\n    __x64_sys_socket+0x72/0xd0\n    do_syscall_64+0xa1/0x5f0\n    entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nInstead of special-casing for refcounted sockets, reject unhashed UDP\nsockets during sockmap updates, as there is no benefit to supporting those.\nThis effectively reverts the commit under Fixes, with two exceptions:\n\n1. sock_map_sk_state_allowed() maintains a fall-through `return true`.\n2. In the spirit of commit b8b8315e39ff (\"bpf, sockmap: Remove unhash\n   handler for BPF sockmap usage\"), the proto::unhash BPF handler is not\n   reintroduced.\n\nHistorical note: this issue is related to commit 67312adc96b5 (\"bpf: reject\nunhashed sockets in bpf_sk_assign\")."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-19T16:34:40.363Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2271276ac5279d2d204be7739a1a28d4ef6cf608"
        },
        {
          "url": "https://git.kernel.org/stable/c/7ffe529e7127411806c8692fb1490f552c629dc2"
        },
        {
          "url": "https://git.kernel.org/stable/c/17b7ef6b86112a4e61cee1e9009a4b318e3225c5"
        },
        {
          "url": "https://git.kernel.org/stable/c/250474c69bc3fc48a5fc21d7c349f279caad947a"
        },
        {
          "url": "https://git.kernel.org/stable/c/8692655da369961128658cf8539334b6a960ecb0"
        },
        {
          "url": "https://git.kernel.org/stable/c/66efd3368ae10d05e08fbe6425b50fdec7186ac7"
        }
      ],
      "title": "bpf, sockmap: Reject unhashed UDP sockets on sockmap update",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68386",
    "datePublished": "2026-08-10T12:04:05.306Z",
    "dateReserved": "2026-07-30T09:28:09.388Z",
    "dateUpdated": "2026-08-19T16:34:40.363Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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