Linux: Out-of-bounds Read
CVE-2026-31558 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.8 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 596c3f8069c4792f22fce8c4452f44410032d910, 878cf6acb4fd8ab4126cf9d369a5bb0e23123418, 47857b05bd50db01e211a1b6f513d57901cd3e6b 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 596c3f8069c4792f22fce8c4452f44410032d910 or 878cf6acb4fd8ab4126cf9d369a5bb0e23123418 or 47857b05bd50db01e211a1b6f513d57901cd3e6b or 2db06c15d8c7a0ccb6108524e16cd9163753f354, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.80 or 6.18.21 or 6.19.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 73516e9da512adc63ba3859fbd82a21f6257348f up to, but not including, 596c3f8069c4792f22fce8c4452f44410032d910; 73516e9da512adc63ba3859fbd82a21f6257348f up to, but not including, 878cf6acb4fd8ab4126cf9d369a5bb0e23123418; 73516e9da512adc63ba3859fbd82a21f6257348f up to, but not including, 47857b05bd50db01e211a1b6f513d57901cd3e6b; 73516e9da512adc63ba3859fbd82a21f6257348f up to, but not including, 2db06c15d8c7a0ccb6108524e16cd9163753f354; 6.10 | 596c3f8069c4792f22fce8c4452f44410032d910, 878cf6acb4fd8ab4126cf9d369a5bb0e23123418, 47857b05bd50db01e211a1b6f513d57901cd3e6b, 2db06c15d8c7a0ccb6108524e16cd9163753f354 |
| Linux | Linux Kernel | 6.10.1 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 6.10; 7.0 | 6.12.80, 6.18.21, 6.19.11 |
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
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: KVM: Make kvm_get_vcpu_by_cpuid() more robust kvm_get_vcpu_by_cpuid() takes a cpuid parameter whose type is int, so cpuid can be negative. Let kvm_get_vcpu_by_cpuid() return NULL for this case so as to make it more robust. This fix an out-of-bounds access to kvm_arch::phyid_map::phys_map[].
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
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.8 High severity
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