GHSA-X32P-2GCJ-5QGH

Vulnerability from github – Published: 2026-05-01 15:30 – Updated: 2026-05-01 15:30
VLAI?
Details

In the Linux kernel, the following vulnerability has been resolved:

netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent

ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT.

The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields.

Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled.

Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43026"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-01T15:16:47Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent\n\nctnetlink_alloc_expect() allocates expectations from a non-zeroing\nslab cache via nf_ct_expect_alloc().  When CTA_EXPECT_NAT is not\npresent in the netlink message, saved_addr and saved_proto are\nnever initialized.  Stale data from a previous slab occupant can\nthen be dumped to userspace by ctnetlink_exp_dump_expect(), which\nchecks these fields to decide whether to emit CTA_EXPECT_NAT.\n\nThe safe sibling nf_ct_expect_init(), used by the packet path,\nexplicitly zeroes these fields.\n\nZero saved_addr, saved_proto and dir in the else branch, guarded\nby IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when\nNAT is enabled.\n\nConfirmed by priming the expect slab with NAT-bearing expectations,\nfreeing them, creating a new expectation without CTA_EXPECT_NAT,\nand observing that the ctnetlink dump emits a spurious\nCTA_EXPECT_NAT containing stale data from the prior allocation.",
  "id": "GHSA-x32p-2gcj-5qgh",
  "modified": "2026-05-01T15:30:37Z",
  "published": "2026-05-01T15:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43026"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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