CVE-2026-89481 (GCVE-0-2026-89481)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-14 12:00
VLAI
Title
nvme-tcp: fix host memory disclosure on R2T for a read command
Summary
In the Linux kernel, the following vulnerability has been resolved: nvme-tcp: fix host memory disclosure on R2T for a read command nvme_tcp_handle_r2t() does not check the direction of the request the R2T refers to. A malicious controller can send an R2T for a READ and the host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the H2CData header and nvme_tcp_try_send_data() sends the request's data buffer. That buffer is the READ destination, so its contents go to the controller. The command then completes normally and nothing is logged. Against a test controller that answers every READ with an R2T, a 4096 byte buffered read returned all 4096 bytes, split over two R2Ts. The pages contained stale kernel data, including an array of struct page pointers. Reject an R2T for a request that is not a write.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < 49a4dcf57608ebf6432dbcb203ed25e7ed581445 (git)
Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < bc4013c7cce58d46f792c8c87bc8c8318a70190e (git)
Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < a4c3c7310156493797c920b10d8648c07aa05403 (git)
Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < 3b3d27670c0c890ba7cf1bc3614cab61bde6d25c (git)
Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < 3a0b05145053a5fad1a2ddb4e4d87b07385e63e5 (git)
Affected: 3f2304f8c6d6ed97849057bd16fee99e434ca796 , < 6efbc52237facda35d2d874fe1765bb4839275d8 (git)
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Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvme-tcp: fix host memory disclosure on R2T for a read command\n\nnvme_tcp_handle_r2t() does not check the direction of the request the\nR2T refers to. A malicious controller can send an R2T for a READ and\nthe host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the\nH2CData header and nvme_tcp_try_send_data() sends the request\u0027s data\nbuffer. That buffer is the READ destination, so its contents go to the\ncontroller.\n\nThe command then completes normally and nothing is logged.\n\nAgainst a test controller that answers every READ with an R2T, a 4096\nbyte buffered read returned all 4096 bytes, split over two R2Ts. The\npages contained stale kernel data, including an array of struct page\npointers.\n\nReject an R2T for a request that is not a write."
        }
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            "version": "3.1"
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              "value": "AV:N - The bug is in the NVMe-over-TCP host PDU receive path (nvme_tcp_recv_skb \u2192 nvme_tcp_handle_r2t). A remote NVMe-oF target or on-path attacker sends an R2T PDU over TCP (port 4420) and the host splices the READ destination buffer back over that socket.\nAC:L - A malicious controller that replies to an in-flight READ with a well-formed R2T always triggers the leak; the reporter reproduced a full 4096-byte disclosure with a test target. No race, special memory layout, or rare config beyond CONFIG_NVME_TCP is required.\nPR:N - NVMe/TCP requires no authentication by default (TLS and DH-HMAC-CHAP are optional and off in stock configs), so the remote peer needs no privileges or credentials on the victim host; it simply answers I/O the host is already sending.\nUI:N - No victim action is required at exploit time; once the host is connected (including via nvmf-autoconnect at boot), ordinary filesystem or block I/O issues READ commands and the malicious target triggers the leak by replying with R2T PDUs.\nS:U - The disclosure is of the host kernel\u0027s own I/O buffers and page-cache pages to the connected target. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - nvme_tcp_try_send_data() splices the READ destination pages to the attacker. Those pages hold stale kernel memory (reproduced: 4096 bytes including struct page pointers). Every subsequent READ can leak another MDTS-sized buffer of recycled kernel pages.\nI:N - The host only transmits existing buffer contents; the bug does not write attacker-controlled data into kernel memory, corrupt kernel structures, or provide a write or control-flow hijack primitive.\nA:N - The malformed R2T path completes the command successfully with nothing logged; the reporter observed a silent disclosure with no oops, panic, hang, or other availability impact."
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    "datePublished": "2026-09-11T19:43:36.589Z",
    "dateReserved": "2026-09-11T19:38:34.711Z",
    "dateUpdated": "2026-09-14T12:00:18.149Z",
    "state": "PUBLISHED"
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      "title": "nvme-tcp: fix host memory disclosure on R2T for a read command",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvme-tcp: fix host memory disclosure on R2T for a read command\n\nnvme_tcp_handle_r2t() does not check the direction of the request the\nR2T refers to. A malicious controller can send an R2T for a READ and\nthe host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the\nH2CData header and nvme_tcp_try_send_data() sends the request\u0027s data\nbuffer. That buffer is the READ destination, so its contents go to the\ncontroller.\n\nThe command then completes normally and nothing is logged.\n\nAgainst a test controller that answers every READ with an R2T, a 4096\nbyte buffered read returned all 4096 bytes, split over two R2Ts. The\npages contained stale kernel data, including an array of struct page\npointers.\n\nReject an R2T for a request that is not a write."
          }
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        "lastModified": "2026-09-14T13:19:04.780",
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      "id": "CVE-2026-89481",
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      "title": "kernel: nvme-tcp: fix host memory disclosure on R2T for a read command",
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      "cve": "CVE-2026-89481",
      "id": "CVE-2026-89481",
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      "product_status:known_affected": "347",
      "product_status:known_not_affected": "6",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89481",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89481.json",
      "version": "5"
    }
  }
}



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