CVE-2026-23095 (GCVE-0-2026-23095)

Vulnerability from cvelistv5 – Published: 2026-02-04 16:08 – Updated: 2026-02-06 16:33
VLAI?
Title
gue: Fix skb memleak with inner IP protocol 0.
Summary
In the Linux kernel, the following vulnerability has been resolved: gue: Fix skb memleak with inner IP protocol 0. syzbot reported skb memleak below. [0] The repro generated a GUE packet with its inner protocol 0. gue_udp_recv() returns -guehdr->proto_ctype for "resubmit" in ip_protocol_deliver_rcu(), but this only works with non-zero protocol number. Let's drop such packets. Note that 0 is a valid number (IPv6 Hop-by-Hop Option). I think it is not practical to encap HOPOPT in GUE, so once someone starts to complain, we could pass down a resubmit flag pointer to distinguish two zeros from the upper layer: * no error * resubmit HOPOPT [0] BUG: memory leak unreferenced object 0xffff888109695a00 (size 240): comm "syz.0.17", pid 6088, jiffies 4294943096 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@.............. backtrace (crc a84b336f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270 __build_skb+0x23/0x60 net/core/skbuff.c:474 build_skb+0x20/0x190 net/core/skbuff.c:490 __tun_build_skb drivers/net/tun.c:1541 [inline] tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636 tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770 tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x45d/0x710 fs/read_write.c:686 ksys_write+0xa7/0x170 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < 886f186328b718400dbf79e1bc8cbcbd710ab766 (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < 380a82d36e37db49fd41ecc378c22fd29392e96a (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < 536f5bbc322eb1e175bdd1ced22b236a951c4d8f (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < f87b9b7a618c82e7465e872eb10e14c803871892 (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < ce569b389a5c78d64788a5ea94560e17fa574b35 (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < 5437a279804ced8088cabb945dba88a26d828f8c (git)
Affected: 37dd0247797b168ad1cc7f5dbec825a1ee66535b , < 9a56796ad258786d3624eef5aefba394fc9bdded (git)
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    Linux Linux Affected: 3.18
Unaffected: 0 , < 3.18 (semver)
Unaffected: 5.10.249 , ≤ 5.10.* (semver)
Unaffected: 5.15.199 , ≤ 5.15.* (semver)
Unaffected: 6.1.162 , ≤ 6.1.* (semver)
Unaffected: 6.6.122 , ≤ 6.6.* (semver)
Unaffected: 6.12.68 , ≤ 6.12.* (semver)
Unaffected: 6.18.8 , ≤ 6.18.* (semver)
Unaffected: 6.19-rc7 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
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              "status": "unaffected",
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngue: Fix skb memleak with inner IP protocol 0.\n\nsyzbot reported skb memleak below. [0]\n\nThe repro generated a GUE packet with its inner protocol 0.\n\ngue_udp_recv() returns -guehdr-\u003eproto_ctype for \"resubmit\"\nin ip_protocol_deliver_rcu(), but this only works with\nnon-zero protocol number.\n\nLet\u0027s drop such packets.\n\nNote that 0 is a valid number (IPv6 Hop-by-Hop Option).\n\nI think it is not practical to encap HOPOPT in GUE, so once\nsomeone starts to complain, we could pass down a resubmit\nflag pointer to distinguish two zeros from the upper layer:\n\n  * no error\n  * resubmit HOPOPT\n\n[0]\nBUG: memory leak\nunreferenced object 0xffff888109695a00 (size 240):\n  comm \"syz.0.17\", pid 6088, jiffies 4294943096\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................\n    00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00  .@..............\n  backtrace (crc a84b336f):\n    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]\n    slab_post_alloc_hook mm/slub.c:4958 [inline]\n    slab_alloc_node mm/slub.c:5263 [inline]\n    kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270\n    __build_skb+0x23/0x60 net/core/skbuff.c:474\n    build_skb+0x20/0x190 net/core/skbuff.c:490\n    __tun_build_skb drivers/net/tun.c:1541 [inline]\n    tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636\n    tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770\n    tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999\n    new_sync_write fs/read_write.c:593 [inline]\n    vfs_write+0x45d/0x710 fs/read_write.c:686\n    ksys_write+0xa7/0x170 fs/read_write.c:738\n    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94\n    entry_SYSCALL_64_after_hwframe+0x77/0x7f"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-06T16:33:16.099Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/886f186328b718400dbf79e1bc8cbcbd710ab766"
        },
        {
          "url": "https://git.kernel.org/stable/c/380a82d36e37db49fd41ecc378c22fd29392e96a"
        },
        {
          "url": "https://git.kernel.org/stable/c/536f5bbc322eb1e175bdd1ced22b236a951c4d8f"
        },
        {
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        },
        {
          "url": "https://git.kernel.org/stable/c/ce569b389a5c78d64788a5ea94560e17fa574b35"
        },
        {
          "url": "https://git.kernel.org/stable/c/5437a279804ced8088cabb945dba88a26d828f8c"
        },
        {
          "url": "https://git.kernel.org/stable/c/9a56796ad258786d3624eef5aefba394fc9bdded"
        }
      ],
      "title": "gue: Fix skb memleak with inner IP protocol 0.",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23095",
    "datePublished": "2026-02-04T16:08:17.990Z",
    "dateReserved": "2026-01-13T15:37:45.963Z",
    "dateUpdated": "2026-02-06T16:33:16.099Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23095\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-04T17:16:20.370\",\"lastModified\":\"2026-02-06T17:16:24.843\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ngue: Fix skb memleak with inner IP protocol 0.\\n\\nsyzbot reported skb memleak below. [0]\\n\\nThe repro generated a GUE packet with its inner protocol 0.\\n\\ngue_udp_recv() returns -guehdr-\u003eproto_ctype for \\\"resubmit\\\"\\nin ip_protocol_deliver_rcu(), but this only works with\\nnon-zero protocol number.\\n\\nLet\u0027s drop such packets.\\n\\nNote that 0 is a valid number (IPv6 Hop-by-Hop Option).\\n\\nI think it is not practical to encap HOPOPT in GUE, so once\\nsomeone starts to complain, we could pass down a resubmit\\nflag pointer to distinguish two zeros from the upper layer:\\n\\n  * no error\\n  * resubmit HOPOPT\\n\\n[0]\\nBUG: memory leak\\nunreferenced object 0xffff888109695a00 (size 240):\\n  comm \\\"syz.0.17\\\", pid 6088, jiffies 4294943096\\n  hex dump (first 32 bytes):\\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................\\n    00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00  .@..............\\n  backtrace (crc a84b336f):\\n    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]\\n    slab_post_alloc_hook mm/slub.c:4958 [inline]\\n    slab_alloc_node mm/slub.c:5263 [inline]\\n    kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270\\n    __build_skb+0x23/0x60 net/core/skbuff.c:474\\n    build_skb+0x20/0x190 net/core/skbuff.c:490\\n    __tun_build_skb drivers/net/tun.c:1541 [inline]\\n    tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636\\n    tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770\\n    tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999\\n    new_sync_write fs/read_write.c:593 [inline]\\n    vfs_write+0x45d/0x710 fs/read_write.c:686\\n    ksys_write+0xa7/0x170 fs/read_write.c:738\\n    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\\n    do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94\\n    entry_SYSCALL_64_after_hwframe+0x77/0x7f\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/380a82d36e37db49fd41ecc378c22fd29392e96a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/536f5bbc322eb1e175bdd1ced22b236a951c4d8f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5437a279804ced8088cabb945dba88a26d828f8c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/886f186328b718400dbf79e1bc8cbcbd710ab766\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9a56796ad258786d3624eef5aefba394fc9bdded\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ce569b389a5c78d64788a5ea94560e17fa574b35\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f87b9b7a618c82e7465e872eb10e14c803871892\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.