Linux: Improper Validation of Array Index
CVE-2026-31776 is a high-severity improper validation of array index vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 950decf59d4e978b60a792ce0b3e1555a608f489, b045ab3dff97edae6d538eeff900a34c098761f8 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 0.12% 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 950decf59d4e978b60a792ce0b3e1555a608f489 or b045ab3dff97edae6d538eeff900a34c098761f8, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.19.12 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | a2dbaeb5c61ef110ceefe0d48fe94d428d3bcf16 up to, but not including, 950decf59d4e978b60a792ce0b3e1555a608f489; a2dbaeb5c61ef110ceefe0d48fe94d428d3bcf16 up to, but not including, b045ab3dff97edae6d538eeff900a34c098761f8; 6.19 | 950decf59d4e978b60a792ce0b3e1555a608f489, b045ab3dff97edae6d538eeff900a34c098761f8 |
| Linux | Linux Kernel | 6.19 up to, but not including, 6.19.12; 7.0 | 6.19.12 |
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
- 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:U/C:H/I:H/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: ALSA: ctxfi: Fix missing SPDIFI1 index handling SPDIF1 DAIO type isn't properly handled in daio_device_index() for hw20k2, and it returned -EINVAL, which ended up with the out-of-bounds array access. Follow the hw20k1 pattern and return the proper index for this type, too.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Array Index
The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
How developers prevent this class of flaw
- Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
- Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND.
More Improper Validation of Array Index vulnerabilities (CWE-129)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Improper Validation of Array Index vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.7 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
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