Linux: Out-of-bounds Read
CVE-2026-64320 is a critical-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions ff815b5e8688dcf68529b7f0fde8de5847f63f1e, 8ae9bb92fc9a712a8d32da9c5fd657101f9b260b, 33b974eb626154ae9348f2bac7de84cb2a3d9dd4 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.8% chance of exploitation within 30 days, higher than 57% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to ff815b5e8688dcf68529b7f0fde8de5847f63f1e or 8ae9bb92fc9a712a8d32da9c5fd657101f9b260b or 33b974eb626154ae9348f2bac7de84cb2a3d9dd4 or 56c021a0869260d04c4b65d1471936aaf9177114, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.96 or 6.18.39 or 7.1.4, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, ff815b5e8688dcf68529b7f0fde8de5847f63f1e; a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, 8ae9bb92fc9a712a8d32da9c5fd657101f9b260b; a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, 33b974eb626154ae9348f2bac7de84cb2a3d9dd4; a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, 56c021a0869260d04c4b65d1471936aaf9177114; a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, a29b316b9bbfd269f323ab4ba9906a894025680f; a07b4970f464f13640e28e16dad6cfa33647cc99 up to, but not including, 53cd102a7a56079b11b897835bd9b94c14e6322c; 4.8 | ff815b5e8688dcf68529b7f0fde8de5847f63f1e, 8ae9bb92fc9a712a8d32da9c5fd657101f9b260b, 33b974eb626154ae9348f2bac7de84cb2a3d9dd4, 56c021a0869260d04c4b65d1471936aaf9177114, a29b316b9bbfd269f323ab4ba9906a894025680f, 53cd102a7a56079b11b897835bd9b94c14e6322c |
| Linux | Linux Kernel | 4.8 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4 | 6.12.96, 6.18.39, 7.1.4 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Out-of-bounds Read vulnerabilities
- 8.4 High severity
- 7.1 High severity
- 7.1 High severity
- 7.7 High severity
- 9.1 Critical severity
- 8.2 High severity
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