CVE-2026-23286 (GCVE-0-2026-23286)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:26 – Updated: 2026-03-25 10:26
VLAI?
Title
atm: lec: fix null-ptr-deref in lec_arp_clear_vccs
Summary
In the Linux kernel, the following vulnerability has been resolved: atm: lec: fix null-ptr-deref in lec_arp_clear_vccs syzkaller reported a null-ptr-deref in lec_arp_clear_vccs(). This issue can be easily reproduced using the syzkaller reproducer. In the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by multiple lec_arp_table entries (e.g., via entry->vcc or entry->recv_vcc). When the underlying VCC is closed, lec_vcc_close() iterates over all ARP entries and calls lec_arp_clear_vccs() for each matched entry. For example, when lec_vcc_close() iterates through the hlists in priv->lec_arp_empty_ones or other ARP tables: 1. In the first iteration, for the first matched ARP entry sharing the VCC, lec_arp_clear_vccs() frees the associated vpriv (which is vcc->user_back) and sets vcc->user_back to NULL. 2. In the second iteration, for the next matched ARP entry sharing the same VCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from vcc->user_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it via `vcc->pop = vpriv->old_pop`, leading to a null-ptr-deref crash. Fix this by adding a null check for vpriv before dereferencing it. If vpriv is already NULL, it means the VCC has been cleared by a previous call, so we can safely skip the cleanup and just clear the entry's vcc/recv_vcc pointers. The entire cleanup block (including vcc_release_async()) is placed inside the vpriv guard because a NULL vpriv indicates the VCC has already been fully released by a prior iteration — repeating the teardown would redundantly set flags and trigger callbacks on an already-closing socket. The Fixes tag points to the initial commit because the entry->vcc path has been vulnerable since the original code. The entry->recv_vcc path was later added by commit 8d9f73c0ad2f ("atm: fix a memory leak of vcc->user_back") with the same pattern, and both paths are fixed here.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e9665986eb127290ceb535bd5d04d7a84265d94f (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 622062f24644b4536d3f437e0cf7a8c4bb421665 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 2d9f57ea29a1f1772373b98a509b44d49fda609e (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7ea92ab075d809ec8a96669a5ecf00f752057875 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 5f1cfea7921f5c126a441d973690eeba52677b64 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.77 , ≤ 6.12.* (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc3 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
            "net/atm/lec.c"
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      "cpeApplicability": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix null-ptr-deref in lec_arp_clear_vccs\n\nsyzkaller reported a null-ptr-deref in lec_arp_clear_vccs().\nThis issue can be easily reproduced using the syzkaller reproducer.\n\nIn the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by\nmultiple lec_arp_table entries (e.g., via entry-\u003evcc or entry-\u003erecv_vcc).\nWhen the underlying VCC is closed, lec_vcc_close() iterates over all\nARP entries and calls lec_arp_clear_vccs() for each matched entry.\n\nFor example, when lec_vcc_close() iterates through the hlists in\npriv-\u003elec_arp_empty_ones or other ARP tables:\n\n1. In the first iteration, for the first matched ARP entry sharing the VCC,\nlec_arp_clear_vccs() frees the associated vpriv (which is vcc-\u003euser_back)\nand sets vcc-\u003euser_back to NULL.\n2. In the second iteration, for the next matched ARP entry sharing the same\nVCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from\nvcc-\u003euser_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\nvia `vcc-\u003epop = vpriv-\u003eold_pop`, leading to a null-ptr-deref crash.\n\nFix this by adding a null check for vpriv before dereferencing\nit. If vpriv is already NULL, it means the VCC has been cleared\nby a previous call, so we can safely skip the cleanup and just\nclear the entry\u0027s vcc/recv_vcc pointers.\n\nThe entire cleanup block (including vcc_release_async()) is placed inside\nthe vpriv guard because a NULL vpriv indicates the VCC has already been\nfully released by a prior iteration \u2014 repeating the teardown would\nredundantly set flags and trigger callbacks on an already-closing socket.\n\nThe Fixes tag points to the initial commit because the entry-\u003evcc path has\nbeen vulnerable since the original code. The entry-\u003erecv_vcc path was later\nadded by commit 8d9f73c0ad2f (\"atm: fix a memory leak of vcc-\u003euser_back\")\nwith the same pattern, and both paths are fixed here."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-25T10:26:45.531Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/e9665986eb127290ceb535bd5d04d7a84265d94f"
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          "url": "https://git.kernel.org/stable/c/622062f24644b4536d3f437e0cf7a8c4bb421665"
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        {
          "url": "https://git.kernel.org/stable/c/101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb"
        }
      ],
      "title": "atm: lec: fix null-ptr-deref in lec_arp_clear_vccs",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23286",
    "datePublished": "2026-03-25T10:26:45.531Z",
    "dateReserved": "2026-01-13T15:37:45.992Z",
    "dateUpdated": "2026-03-25T10:26:45.531Z",
    "state": "PUBLISHED"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23286\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-25T11:16:23.393\",\"lastModified\":\"2026-03-25T15:41:33.977\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\natm: lec: fix null-ptr-deref in lec_arp_clear_vccs\\n\\nsyzkaller reported a null-ptr-deref in lec_arp_clear_vccs().\\nThis issue can be easily reproduced using the syzkaller reproducer.\\n\\nIn the ATM LANE (LAN Emulation) module, the same atm_vcc can be shared by\\nmultiple lec_arp_table entries (e.g., via entry-\u003evcc or entry-\u003erecv_vcc).\\nWhen the underlying VCC is closed, lec_vcc_close() iterates over all\\nARP entries and calls lec_arp_clear_vccs() for each matched entry.\\n\\nFor example, when lec_vcc_close() iterates through the hlists in\\npriv-\u003elec_arp_empty_ones or other ARP tables:\\n\\n1. In the first iteration, for the first matched ARP entry sharing the VCC,\\nlec_arp_clear_vccs() frees the associated vpriv (which is vcc-\u003euser_back)\\nand sets vcc-\u003euser_back to NULL.\\n2. In the second iteration, for the next matched ARP entry sharing the same\\nVCC, lec_arp_clear_vccs() is called again. It obtains a NULL vpriv from\\nvcc-\u003euser_back (via LEC_VCC_PRIV(vcc)) and then attempts to dereference it\\nvia `vcc-\u003epop = vpriv-\u003eold_pop`, leading to a null-ptr-deref crash.\\n\\nFix this by adding a null check for vpriv before dereferencing\\nit. If vpriv is already NULL, it means the VCC has been cleared\\nby a previous call, so we can safely skip the cleanup and just\\nclear the entry\u0027s vcc/recv_vcc pointers.\\n\\nThe entire cleanup block (including vcc_release_async()) is placed inside\\nthe vpriv guard because a NULL vpriv indicates the VCC has already been\\nfully released by a prior iteration \u2014 repeating the teardown would\\nredundantly set flags and trigger callbacks on an already-closing socket.\\n\\nThe Fixes tag points to the initial commit because the entry-\u003evcc path has\\nbeen vulnerable since the original code. The entry-\u003erecv_vcc path was later\\nadded by commit 8d9f73c0ad2f (\\\"atm: fix a memory leak of vcc-\u003euser_back\\\")\\nwith the same pattern, and both paths are fixed here.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/101bacb303e89dc2e0640ae6a5e0fb97c4eb45bb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2d9f57ea29a1f1772373b98a509b44d49fda609e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5f1cfea7921f5c126a441d973690eeba52677b64\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/622062f24644b4536d3f437e0cf7a8c4bb421665\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7ea92ab075d809ec8a96669a5ecf00f752057875\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e9665986eb127290ceb535bd5d04d7a84265d94f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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