FKIE_CVE-2026-43026

Vulnerability from fkie_nvd - Published: 2026-05-01 15:16 - Updated: 2026-05-01 15:24
Severity ?
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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": "CVE-2026-43026",
  "lastModified": "2026-05-01T15:24:14.893",
  "metrics": {},
  "published": "2026-05-01T15:16:47.033",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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