nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64320
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:13 UTC
Updated2026-07-27 05:16:42 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS: 0.007280000 probability, percentile 0.504950000 (date 2026-07-29)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a07b4970f464f13640e28e16dad6cfa33647cc99 33b974eb626154ae9348f2bac7de84cb2a3d9dd4 git Not specified
CNA Linux Linux affected a07b4970f464f13640e28e16dad6cfa33647cc99 56c021a0869260d04c4b65d1471936aaf9177114 git Not specified
CNA Linux Linux affected a07b4970f464f13640e28e16dad6cfa33647cc99 a29b316b9bbfd269f323ab4ba9906a894025680f git Not specified
CNA Linux Linux affected a07b4970f464f13640e28e16dad6cfa33647cc99 53cd102a7a56079b11b897835bd9b94c14e6322c git Not specified
CNA Linux Linux affected 4.8 Not specified
CNA Linux Linux unaffected 4.8 semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/56c021a0869260d04c4b65d1471936aaf9177114 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/53cd102a7a56079b11b897835bd9b94c14e6322c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/33b974eb626154ae9348f2bac7de84cb2a3d9dd4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a29b316b9bbfd269f323ab4ba9906a894025680f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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