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netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-43026

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-2026-43026

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": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "a5a89db6981a1ddf2314bf50cb49db5a3146185f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "1c2ebdeff8d088a2e47ae25d7b38447249adace2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "a64b7bf84b4d5ea54218c5d374ec87fff9000f43",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "2898080c054ea4d6ddfaaf21bbedbc229a9a8376",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "fd002ff2ea030cbfb0188a11b3c60ce7f84485f4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "929f7a9a7aad9404a5867216c3f8738232355b38",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "076a0ca02644657b13e4af363f487ced2942e9cb",
        "lessThan": "35177c6877134a21315f37d57a5577846225623e",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_conntrack_netlink.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.4"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.4",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.168",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.134",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.81",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.22",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.12",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_conntrack_netlink.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-43026

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#28337 · Revision 1
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