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l2tp: fix tunnel and session refcount leak on seq_file release

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: l2tp: fix tunnel and session refcount leak on seq_file release In pppol2tp_proc_open() and l2tp_dfs_seq_open(), iteration state (pd->tunnel and pd->session) is kept in seq_file private data to allow iteration across multiple read() system calls. However, if userspace closes /proc/net/pppol2tp or /sys/kernel/debug/l2tp/tunnels before reading to end-of-file (EOF), any tunnel or session reference stored in pd->tunnel / pd->session is left un-dropped when seq_file private data is freed. Fix this by dropping any remaining pd->tunnel and pd->session references in pppol2tp_proc_release() and l2tp_dfs_seq_release() when closing the file.

Announced Source revision 1
Original source ↗

CVE-2026-74735

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-2026-74735

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": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
        "lessThan": "bd897e414451fb34dfdf08b31899180e5ab7149b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
        "lessThan": "bdf83613781956cc39798ed08321f74ab0467f4d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
        "lessThan": "8c4fde01bcf91f22b9c7ded8c3e14addd7ddd500",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
        "lessThan": "ebe2774e956482dd3c70b8991f6f7654356339e6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
        "lessThan": "9006c116dd111d457bf5d074990210f70a4ad2c8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "f6104e9ae04462523c372928b1173766a771ef95",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "7f8e401f9e612df2a95c1ef76217c00181389bb5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c712ed63e9b33d9a282fbd92ce25c64918c3129f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9a8863e8a8def9d88583cd9c60db38a008e6b8cf",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3.16.60",
        "lessThan": "3.17",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "4.16.6",
        "lessThan": "4.17",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "net/l2tp/l2tp_debugfs.c",
      "net/l2tp/l2tp_ppp.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.17"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.17",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "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": "7.1.10",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/l2tp/l2tp_debugfs.c",
      "net/l2tp/l2tp_ppp.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74735

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46598 · Revision 1
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Publisher date
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