FKIE_CVE-2026-74735

Vulnerability from fkie_nvd - Published: 2026-08-26 15:16 - Updated: 2026-08-26 15:16
Severity
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9006c116dd111d457bf5d074990210f70a4ad2c8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ebe2774e956482dd3c70b8991f6f7654356339e6
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/l2tp/l2tp_debugfs.c",
            "net/l2tp/l2tp_ppp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ebe2774e956482dd3c70b8991f6f7654356339e6",
              "status": "affected",
              "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
              "versionType": "git"
            },
            {
              "lessThan": "9006c116dd111d457bf5d074990210f70a4ad2c8",
              "status": "affected",
              "version": "0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443",
              "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"
            },
            {
              "lessThan": "3.17",
              "status": "affected",
              "version": "3.16.60",
              "versionType": "semver"
            },
            {
              "lessThan": "4.17",
              "status": "affected",
              "version": "4.16.6",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/l2tp/l2tp_debugfs.c",
            "net/l2tp/l2tp_ppp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.17"
            },
            {
              "lessThan": "4.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: fix tunnel and session refcount leak on seq_file release\n\nIn pppol2tp_proc_open() and l2tp_dfs_seq_open(), iteration state\n(pd-\u003etunnel and pd-\u003esession) is kept in seq_file private data to allow\niteration across multiple read() system calls.\n\nHowever, if userspace closes /proc/net/pppol2tp or /sys/kernel/debug/l2tp/tunnels\nbefore reading to end-of-file (EOF), any tunnel or session reference stored in\npd-\u003etunnel / pd-\u003esession is left un-dropped when seq_file private data is freed.\n\nFix this by dropping any remaining pd-\u003etunnel and pd-\u003esession references in\npppol2tp_proc_release() and l2tp_dfs_seq_release() when closing the file."
    }
  ],
  "id": "CVE-2026-74735",
  "lastModified": "2026-08-26T15:16:52.057",
  "metrics": {},
  "published": "2026-08-26T15:16:52.057",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9006c116dd111d457bf5d074990210f70a4ad2c8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ebe2774e956482dd3c70b8991f6f7654356339e6"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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