Linux: Out-of-bounds Write
CVE-2026-31690 is a high-severity out-of-bounds write 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 fbdb43f6bb2a15ed382d6eb0ef82c8b07b0d47bb, bd15a5deb5a7251dc1a0cf9186f0253f7eacdb97, 88c4bd90725557796c15878b7cb70066e9e6b5ab 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 fbdb43f6bb2a15ed382d6eb0ef82c8b07b0d47bb or bd15a5deb5a7251dc1a0cf9186f0253f7eacdb97 or 88c4bd90725557796c15878b7cb70066e9e6b5ab, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.23 or 6.19.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e4b3cbd840e565484d0ad8d260d27c057466ed17 up to, but not including, fbdb43f6bb2a15ed382d6eb0ef82c8b07b0d47bb; e4b3cbd840e565484d0ad8d260d27c057466ed17 up to, but not including, bd15a5deb5a7251dc1a0cf9186f0253f7eacdb97; e4b3cbd840e565484d0ad8d260d27c057466ed17 up to, but not including, 88c4bd90725557796c15878b7cb70066e9e6b5ab; 6.15 | fbdb43f6bb2a15ed382d6eb0ef82c8b07b0d47bb, bd15a5deb5a7251dc1a0cf9186f0253f7eacdb97, 88c4bd90725557796c15878b7cb70066e9e6b5ab |
| Linux | Linux Kernel | 6.15 up to, but not including, 6.18.23; 6.19 up to, but not including, 6.19.13; 7.0 | 6.18.23, 6.19.13 |
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: firmware: thead: Fix buffer overflow and use standard endian macros Addresses two issues in the TH1520 AON firmware protocol driver: 1. Fix a potential buffer overflow where the code used unsafe pointer arithmetic to access the 'mode' field through the 'resource' pointer with an offset. This was flagged by Smatch static checker as: "buffer overflow 'data' 2 <= 3" 2. Replace custom RPC_SET_BE* and RPC_GET_BE* macros with standard kernel endianness conversion macros (cpu_to_be16, etc.) for better portability and maintainability. The functionality was re-tested with the GPU power-up sequence, confirming the GPU powers up correctly and the driver probes successfully. [ 12.702370] powervr ffef400000.gpu: [drm] loaded firmware powervr/rogue_36.52.104.182_v1.fw [ 12.711043] powervr ffef400000.gpu: [drm] FW version v1.0 (build 6645434 OS) [ 12.719787] [drm] Initialized powervr 1.0.0 for ffef400000.gpu on minor 0
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Out-of-bounds Write vulnerabilities
- 7.5 High severity
- 8.1 High severity
- 8.2 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
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