Linux: Out-of-bounds Read
CVE-2026-64477 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ebc300b7ee0c669fa76a7a8858298ff32e296103, be1567992417dc92133e74126de7a6066c825ac9, 58c5ec23b1a238eb75cb0aba6f69d8f9e68ef0b2 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 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to ebc300b7ee0c669fa76a7a8858298ff32e296103 or be1567992417dc92133e74126de7a6066c825ac9 or 58c5ec23b1a238eb75cb0aba6f69d8f9e68ef0b2 or fc16126cc11d9f507130bf84ab137ee0938c900e, 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e13db55b5a0d447dea63cde772c1078405bbbf96 up to, but not including, ebc300b7ee0c669fa76a7a8858298ff32e296103; e13db55b5a0d447dea63cde772c1078405bbbf96 up to, but not including, be1567992417dc92133e74126de7a6066c825ac9; e13db55b5a0d447dea63cde772c1078405bbbf96 up to, but not including, 58c5ec23b1a238eb75cb0aba6f69d8f9e68ef0b2; e13db55b5a0d447dea63cde772c1078405bbbf96 up to, but not including, fc16126cc11d9f507130bf84ab137ee0938c900e; 6.11 | ebc300b7ee0c669fa76a7a8858298ff32e296103, be1567992417dc92133e74126de7a6066c825ac9, 58c5ec23b1a238eb75cb0aba6f69d8f9e68ef0b2, fc16126cc11d9f507130bf84ab137ee0938c900e |
| Linux | Linux Kernel | 6.11 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; 7.2 | 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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: x86,fs/resctrl: Prevent out-of-bounds access while offlining CPU when SNC enabled The architecture updates the cpu_mask in a domain's header to track which online CPUs are associated with the domain. When this mask becomes empty the architecture initiates offline of the domain that includes calling on resctrl fs to offline the domain. If it is a monitoring domain in which LLC occupancy is tracked resctrl fs forces the limbo handler to clear all busy RMID state associated with the domain. The limbo handler always reads the current event value associated with a busy RMID irrespective of it being checked as part of regular "is it still busy" check or whether it will be forced released anyway. When reading an RMID on a system with SNC enabled the "logical RMID" is converted to the "physical RMID" and this conversion requires the NUMA node ID of the resctrl monitoring domain that is in turn determined by querying the NUMA node ID of any CPU belonging to the monitoring domain. When the monitoring domain is going offline its cpu_mask is empty causing the NUMA node ID query via cpu_to_node() to be done with "nr_cpu_ids" as argument resulting in an out-of-bounds access. Refactor the limbo handler to skip reading the RMID when the RMID will just be forced to no longer be dirty in the domain anyway. Add a safety check to the architecture's RMID reader to protect against this scenario.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Out-of-bounds Read vulnerabilities
- 8.4 High severity
- 7.1 High severity
- 7.7 High severity
- 9.1 Critical severity
- 8.2 High severity
- 8.8 High severity
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