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gue: Fix skb memleak with inner IP protocol 0.

Type: advisorySource: Official CVE List1 source record

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

Announced Source revision 1
Original source ↗

CVE-2026-23095

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-23095

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "886f186328b718400dbf79e1bc8cbcbd710ab766",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "380a82d36e37db49fd41ecc378c22fd29392e96a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "536f5bbc322eb1e175bdd1ced22b236a951c4d8f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "f87b9b7a618c82e7465e872eb10e14c803871892",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "ce569b389a5c78d64788a5ea94560e17fa574b35",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "5437a279804ced8088cabb945dba88a26d828f8c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "37dd0247797b168ad1cc7f5dbec825a1ee66535b",
        "lessThan": "9a56796ad258786d3624eef5aefba394fc9bdded",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv4/fou_core.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.18"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.18",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.249",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.199",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.162",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.122",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.68",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.8",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv4/fou_core.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-23095

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#39749 · Revision 1
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Publisher date
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