CVE-2026-89969 (GCVE-0-2026-89969)
Vulnerability from cvelistv5
Published
2026-09-16 10:32
Modified
2026-10-19 08:55
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: fix out-of-bounds write when receiving an over-long PDU nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte queue->pdu union, then computes the remaining payload length as queue->left = hdr->hlen - queue->offset + hdgst; and reads that many more bytes into &queue->pdu + queue->offset, without ever bounding the result against sizeof(queue->pdu). A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the union. Once a header digest has been negotiated (hdgst = 4), a second ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the 128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and queue->data_digest. Those bytes are attacker-controlled (an ICReq carries no digest), and the duplicate ICReq is only rejected later, after the overflow. A remote unauthenticated host can thus corrupt kernel memory adjacent to the receive buffer. Reject any PDU whose declared length would read past the end of queue->pdu before the second recv.
References
Impacted products
Vendor Product Version
Linux Linux Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
Version: 872d26a391da92ed8f0c0f5cb5fef428067b7f30
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/nvme/target/tcp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.0"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
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              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
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              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
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              "version": "7.2.5",
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "versionEndExcluding": "5.10.270",
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                  "vulnerable": true
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                  "versionEndExcluding": "7.3",
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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: fix out-of-bounds write when receiving an over-long PDU\n\nnvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte\nqueue-\u003epdu union, then computes the remaining payload length as\n\n\tqueue-\u003eleft = hdr-\u003ehlen - queue-\u003eoffset + hdgst;\n\nand reads that many more bytes into \u0026queue-\u003epdu + queue-\u003eoffset, without\never bounding the result against sizeof(queue-\u003epdu).\n\nA struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the\nunion. Once a header digest has been negotiated (hdgst = 4), a second\nICReq passes the hlen == nvmet_tcp_pdu_size() check but yields\nqueue-\u003eleft = 128 - 8 + 4 = 124, so bytes 8..132 are written into the\n128-byte buffer -- 4 bytes past its end, over queue-\u003ehdr_digest and\nqueue-\u003edata_digest. Those bytes are attacker-controlled (an ICReq\ncarries no digest), and the duplicate ICReq is only rejected later,\nafter the overflow. A remote unauthenticated host can thus corrupt\nkernel memory adjacent to the receive buffer.\n\nReject any PDU whose declared length would read past the end of\nqueue-\u003epdu before the second recv."
        }
      ],
      "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 flaw is in nvmet-tcp, an in-kernel NVMe-over-TCP target that accepts remote TCP connections; nvmet_tcp_try_recv_pdu() copies attacker-controlled PDU bytes from the socket, so the overflow is reachable from any network peer that can connect to an exposed NVMe-oF TCP port (typical cloud/storage-server deployment).\nAC:L - The attacker enables header digest in the first ICReq (the target copies the initiator\u0027s digest flags with no extra configuration), then sends a second 128-byte ICReq; queue-\u003eleft becomes 124 and four attacker-controlled bytes are written past queue-\u003epdu with no race or condition outside attacker control.\nPR:N - The overflow fires on a duplicate ICReq after TCP accept and digest negotiation, before NVMe Connect, host NQN allow-list, or DH-HMAC-CHAP in-band authentication; no Linux credentials or capabilities on the target are required.\nUI:N - Exploitation requires only attacker-sent NVMe/TCP PDUs to an already listening target port; no victim user action such as mounting a filesystem or opening a device is needed.\nS:U - The out-of-bounds write corrupts fields of the host\u0027s nvmet_tcp_queue in kernel memory and does not cross a VM, hypervisor, container, or IOMMU security boundary.\nC:H - Attacker-controlled 4-byte overflow into kernel memory adjacent to queue-\u003epdu is memory corruption that, per kernel guidance, can be leveraged for information disclosure (including by clearing hdr_digest so later verify_hdgst is skipped and by controlling the persisted digest-flag bytes).\nI:H - This is an attacker-controlled out-of-bounds write past the 128-byte queue-\u003epdu union into adjacent kernel fields (hdr_digest and data_digest); per kernel guidance an OOB write is High integrity impact and can disable PDU digest verification before the duplicate ICReq is rejected.\nA:H - After the overflow, nvmet_tcp_done_recv_pdu() returns -EPROTO and nvmet_tcp_socket_error() calls nvmet_ctrl_fatal_error() once a controller exists (e.g. after unauthenticated Discovery Connect), taking down the NVMe target; the kernel memory corruption can also oops, and the trigger is remotely repeatable."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:55:42.820Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a3f0bcfbaf3312a5754d1ce020a07d394669eb25"
        },
        {
          "url": "https://git.kernel.org/stable/c/4f84d42c53c49557fb1ef285c683b0a81b576c74"
        },
        {
          "url": "https://git.kernel.org/stable/c/58dc6035b79c4c73c0cbf9ec9f68a7f117b2b3e6"
        },
        {
          "url": "https://git.kernel.org/stable/c/cf5f39d2b58f97e0cd1829c4a6aeef17f1607cca"
        },
        {
          "url": "https://git.kernel.org/stable/c/3a385e0c39efbe34db8edd95900c123113ae3450"
        },
        {
          "url": "https://git.kernel.org/stable/c/dbc4acbdb3ca8c81441368ad7409b8f77d4de8f6"
        },
        {
          "url": "https://git.kernel.org/stable/c/d95d342bc0ea82dc79e6362b2f1f997431750e4c"
        },
        {
          "url": "https://git.kernel.org/stable/c/14cc5a7e77731497d5bea70f3bb05df7eda982e4"
        }
      ],
      "title": "nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89969",
    "datePublished": "2026-09-16T10:32:49.603Z",
    "dateReserved": "2026-09-11T19:38:34.778Z",
    "dateUpdated": "2026-10-19T08:55:42.820Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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