CVE-2026-64534 (GCVE-0-2026-64534)
Vulnerability from cvelistv5
Published
2026-07-27 06:32
Modified
2026-08-05 12:42
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected, nvmet_req_uninit() is called unconditionally. However, if the command arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init() had returned false and percpu_ref_tryget_live() was never executed. The unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a refcount underflow, leading to a WARNING in percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and eventually a permanent workqueue deadlock. Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling nvmet_req_uninit(), matching the existing pattern in nvmet_tcp_execute_request().
References
Impacted products
Vendor Product Version
Linux Linux Version: 91edfca6f8b364d60cde3ddefaf7d03ddf35774b
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: fda871c0ba5d2eed2cd1c881573168129da70058
Version: 4b17476d809273617d3317fa0d4ae78aa488d760
Version: 5.10.20   ≤
Version: 5.11.3   ≤
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/nvme/target/tcp.c"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path\n\nIn nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected,\nnvmet_req_uninit() is called unconditionally. However, if the command\narrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init()\nhad returned false and percpu_ref_tryget_live() was never executed. The\nunconditional percpu_ref_put() inside nvmet_req_uninit() then causes a\nrefcount underflow, leading to a WARNING in\npercpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and\neventually a permanent workqueue deadlock.\n\nCheck cmd-\u003eflags \u0026 NVMET_TCP_F_INIT_FAILED before calling\nnvmet_req_uninit(), matching the existing pattern in\nnvmet_tcp_execute_request()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable NVMe/TCP target receive path processes attacker-supplied ICReq, CapsuleCmd, inline payload, and digest data over an Internet-routable TCP connection.\nAC:L - The attacker can negotiate data digests and reliably send a rejected write command with inline data followed by an incorrect digest; no race or condition outside the attacker\u0027s control is required.\nPR:N - A malformed CapsuleCmd can trigger this path before CONNECT, host-NQN ACL evaluation, or DH-HMAC-CHAP authentication, so the remote attacker needs no credentials or privileges.\nUI:N - The target processes the malicious protocol sequence automatically without any victim action.\nS:U - The vulnerable transport and the affected kernel memory, execution, and storage resources belong to the same target-host security authority.\nC:H - The unmatched reference decrement can offset a legitimate in-flight request reference, allowing command structures and SGL pages to be freed while backend I/O still uses them; this UAF can expose arbitrary reused kernel memory.\nI:H - The premature freeing of request structures and I/O pages can let backend operations write through reallocated memory or corrupt completion control state, making arbitrary kernel writes and control-flow hijacking defensible.\nA:H - The basic trigger causes a submission-queue refcount underflow and permanent workqueue deadlock, while UAF variants can crash the kernel; unauthenticated attackers can repeat the trigger across connections."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:42:44.214Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf"
        },
        {
          "url": "https://git.kernel.org/stable/c/ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e"
        },
        {
          "url": "https://git.kernel.org/stable/c/c7874dad84b20433c0fe3919f291a762d40de08b"
        },
        {
          "url": "https://git.kernel.org/stable/c/e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1"
        },
        {
          "url": "https://git.kernel.org/stable/c/d306da8833e75f669d93424fd84940236f3850bc"
        },
        {
          "url": "https://git.kernel.org/stable/c/2ed3c9d955e8cd6361f130623baa664a75fb345f"
        },
        {
          "url": "https://git.kernel.org/stable/c/4606467a75cfc16721937272ed29462a750b60c8"
        }
      ],
      "title": "nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64534",
    "datePublished": "2026-07-27T06:32:34.301Z",
    "dateReserved": "2026-07-19T15:36:31.795Z",
    "dateUpdated": "2026-08-05T12:42:44.214Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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