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ipv6: sit: reload inner IPv6 header after GSO offloads

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv6: sit: reload inner IPv6 header after GSO offloads ipip6_tunnel_xmit() caches the inner IPv6 header pointer at function entry and continues using it after iptunnel_handle_offloads(). For GSO skbs, iptunnel_handle_offloads() calls skb_header_unclone(). When the skb header is cloned, skb_header_unclone() can call pskb_expand_head(), which may move the skb head. The pskb_expand_head() contract requires pointers into the skb header to be reloaded after the call. If the later skb_realloc_headroom() branch is not taken, SIT uses the stale iph6 pointer to read the inner hop limit and DS field. That can read from a freed skb head after the old head's remaining clone is released. Reload iph6 after the offload helper succeeds and before subsequent reads from the inner IPv6 header. Keep the existing reload after skb_realloc_headroom(), since that branch can also replace the skb.

Announced Source revision 1
Original source ↗

CVE-2026-53228

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-2026-53228

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": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "fddd41445a0537b093e6b3f6232c9933cad1e48b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "1132e5edc2866c3530be17622153a597095f0e43",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "9c67b44edb3598d234efae6e44649eb993c03da5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "0bfa7bba1f41aaf5f0604dc712bb4701493e3aa0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "59f80c919713250fe5d25a4d9aea4e49580fa1d4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "2fa49b2715e1bad12ce3b0fa64e234d9582c8193",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "cb658c2f5f7977c2a1c77c9f239f4bc8196edb5c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "14909664e4e192f4c6f6fcdccd9919af7cf783ab",
        "lessThan": "f0e42f0c4337b1f220de1ddd63f47197c7dee4de",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/sit.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": "5.10.259",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.210",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.176",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.143",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.94",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.36",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.13",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/sit.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-53228

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#40787 · Revision 1
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Publisher date
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