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netfilter: nf_nat_sip: reload possible stale data pointer

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_nat_sip: reload possible stale data pointer quoting sashiko: ------------------------------------------------------------------------ [..] noticed a potential memory bug and header corruption involving the SIP NAT helper. In net/netfilter/nf_nat_sip.c:nf_nat_sip(): if (skb_ensure_writable(skb, skb->len)) { nf_ct_helper_log(skb, ct, "cannot mangle packet"); return NF_DROP; } uh = (void *)skb->data + protoff; uh->dest = ct_sip_info->forced_dport; if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, 0, 0, NULL, 0)) { If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the old data buffer is freed. However, nf_nat_sip() fails to update *dptr to point to the new buffer. It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP packet, which would overwrite the sequence number with a checksum update. ------------------------------------------------------------------------ nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen. But clones are possible, so rebuild dptr. Disable nf_nat_mangle_udp_packet() branch for TCP streams. It doesn't look like this can ever happen, else we should have received bug reports about this, so just check the conntrack is UDP and drop otherwise. The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages, so I don't think this is ever expected to be true for a TCP stream.

Announced Source revision 1
Original source ↗

CVE-2026-72251

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-2026-72251

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": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "bded21a4bf9bf86a79148be735723a97ca9a7532",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "dc11f26685aa850f237226f0f463647aea58ab7c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "e38143c9b477f2968024c47c647dd4456a40aff1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "57e4e29644ec054d7021d296407e7ddd844afea2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "2bcf2c5052fb5e73e255140ab43f056aef409c27",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7266507d89991fa1e989283e4e032c6d9357fe26",
        "lessThan": "77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_nat_sip.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.9"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.9",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.261",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.212",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.178",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.145",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.97",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.40",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/netfilter/nf_nat_sip.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-72251

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#32995 · Revision 1
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Publisher date
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