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CVE-2026-64320 (GCVE-0-2026-64320)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-08-17 04:53
VLAI
Title
nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page
Summary
In the Linux kernel, the following vulnerability has been resolved: nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page nvmet_execute_disc_get_log_page() validates only the dword alignment of the host-supplied Log Page Offset (lpo). The 64-bit offset is then added to a small kzalloc'd buffer that holds the discovery log page and the result is passed straight to nvmet_copy_to_sgl(), which memcpy()s data_len bytes out to the host with no source-side bound check: u64 offset = nvmet_get_log_page_offset(req->cmd); /* 64-bit host */ size_t data_len = nvmet_get_log_page_len(req->cmd); /* 32-bit host */ ... if (offset & 0x3) { ... } /* only check */ ... alloc_len = sizeof(*hdr) + entry_size * discovery_log_entries(req); buffer = kzalloc(alloc_len, GFP_KERNEL); ... status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len); The Discovery controller is unauthenticated -- nvmet_host_allowed() returns true unconditionally for the discovery subsystem -- so the call is reachable pre-authentication by any TCP/RDMA/FC peer that can reach the nvmet target. With a discovery log page of ~1 KiB, an attacker requesting up to 4 KiB starting at offset == alloc_len reads the next slab page out and gets its content returned over the fabric (an empirical run on a default nvmet-tcp loopback target leaked 81 canonical kernel pointers in one Get Log Page response). Pointing the offset at unmapped kernel memory faults the in-kernel memcpy and crashes (or panics, on panic_on_oops=1) the target host instead. The attacker-controlled source-side offset pattern "nvmet_copy_to_sgl(req, 0, buffer + ATTACKER_OFFSET, ...)" is unique to nvmet_execute_disc_get_log_page in the entire nvmet codebase: every other Get Log Page handler in admin-cmd.c either ignores lpo (and silently starts every response at offset 0) or tracks a local destination offset with a fixed source pointer. Validate the host-supplied offset against the log page size, cap the copy length to what is actually available, and zero-fill any remainder of the host transfer buffer. The zero-fill matches the existing short-response pattern in nvmet_execute_get_log_changed_ns() (admin-cmd.c) and prevents leaking transport SGL contents when the host asks for more bytes than the log page contains.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a07b4970f464f13640e28e16dad6cfa33647cc99 , < 33b974eb626154ae9348f2bac7de84cb2a3d9dd4 (git)
Affected: a07b4970f464f13640e28e16dad6cfa33647cc99 , < 56c021a0869260d04c4b65d1471936aaf9177114 (git)
Affected: a07b4970f464f13640e28e16dad6cfa33647cc99 , < a29b316b9bbfd269f323ab4ba9906a894025680f (git)
Affected: a07b4970f464f13640e28e16dad6cfa33647cc99 , < 53cd102a7a56079b11b897835bd9b94c14e6322c (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.8
Unaffected: 0 , < 4.8 (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page\n\nnvmet_execute_disc_get_log_page() validates only the dword alignment\nof the host-supplied Log Page Offset (lpo).  The 64-bit offset is then\nadded to a small kzalloc\u0027d buffer that holds the discovery log page\nand the result is passed straight to nvmet_copy_to_sgl(), which\nmemcpy()s data_len bytes out to the host with no source-side bound\ncheck:\n\n    u64 offset      = nvmet_get_log_page_offset(req-\u003ecmd);  /* 64-bit host */\n    size_t data_len = nvmet_get_log_page_len(req-\u003ecmd);     /* 32-bit host */\n    ...\n    if (offset \u0026 0x3) { ... }                               /* only check */\n    ...\n    alloc_len = sizeof(*hdr) + entry_size * discovery_log_entries(req);\n    buffer = kzalloc(alloc_len, GFP_KERNEL);\n    ...\n    status = nvmet_copy_to_sgl(req, 0, buffer + offset, data_len);\n\nThe Discovery controller is unauthenticated -- nvmet_host_allowed()\nreturns true unconditionally for the discovery subsystem -- so the call\nis reachable pre-authentication by any TCP/RDMA/FC peer that can reach\nthe nvmet target.  With a discovery log page of ~1 KiB, an attacker\nrequesting up to 4 KiB starting at offset == alloc_len reads the next\nslab page out and gets its content returned over the fabric (an\nempirical run on a default nvmet-tcp loopback target leaked 81\ncanonical kernel pointers in one Get Log Page response).  Pointing the\noffset at unmapped kernel memory faults the in-kernel memcpy and\ncrashes (or panics, on panic_on_oops=1) the target host instead.\n\nThe attacker-controlled source-side offset pattern\n\"nvmet_copy_to_sgl(req, 0, buffer + ATTACKER_OFFSET, ...)\" is unique\nto nvmet_execute_disc_get_log_page in the entire nvmet codebase: every\nother Get Log Page handler in admin-cmd.c either ignores lpo (and\nsilently starts every response at offset 0) or tracks a local\ndestination offset with a fixed source pointer.\n\nValidate the host-supplied offset against the log page size, cap the\ncopy length to what is actually available, and zero-fill any remainder\nof the host transfer buffer.  The zero-fill matches the existing\nshort-response pattern in nvmet_execute_get_log_changed_ns()\n(admin-cmd.c) and prevents leaking transport SGL contents when the\nhost asks for more bytes than the log page contains."
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-08T12:44:23+00:00",
      "cve": "CVE-2026-64320",
      "id": "CVE-2026-64320",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:fixed": "762",
      "product_status:known_affected": "50",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64320.json",
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    }
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}



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