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fou: Fix use-after-free in fou_create()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().

Announced Source revision 1
Original source ↗

CVE-2026-74496

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-2026-74496

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": "23461551c00628c3f3fe9cf837bf53cf8f212b63",
        "lessThan": "0ee628a58d83e571f36ec9f07624d6845e420c50",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "a6fca682cfa2041e31aa72cc397c4a1406eb7468",
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        "lessThan": "b3f9c3e60aa25453774f899d25b5e61dd0bec1d5",
        "versionType": "git"
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        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "9042867d4701728f0c6527215b11471759904d8f",
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      {
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        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv4/fou_core.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": "5.10.271",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.222",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.53",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.8",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv4/fou_core.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74496

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33180 · Revision 1
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Publisher date
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