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CVE-2026-31780NVD status: Analyzed

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-31780 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 34a23fd9ddd683a03c7e8cc0ceded3e59e354b99, 549f02d8ec94d39092ab6d9b103d0d6783a4b024, bfbddeadd4779651403035ee177ae2f22f9f5521 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 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 34a23fd9ddd683a03c7e8cc0ceded3e59e354b99 or 549f02d8ec94d39092ab6d9b103d0d6783a4b024 or bfbddeadd4779651403035ee177ae2f22f9f5521 or 9907ac9b9a18b92fc34b9e4cb9e10f208dc1d3f7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.134, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxc5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, 34a23fd9ddd683a03c7e8cc0ceded3e59e354b99; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, 549f02d8ec94d39092ab6d9b103d0d6783a4b024; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, bfbddeadd4779651403035ee177ae2f22f9f5521; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, 9907ac9b9a18b92fc34b9e4cb9e10f208dc1d3f7; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, c97b2a00059608592ad0d86fbb813a4f8cf9464b; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, d8388614de613c28eeb659c10115060a83739924; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, 0c7f21d8bd2f93998b72b7a7f93152336aeca4dd; c5c77ba18ea66aa05441c71e38473efb787705a4 up to, but not including, d049e56b1739101d1c4d81deedb269c52a8dbba0; and 1 more ranges34a23fd9ddd683a03c7e8cc0ceded3e59e354b99, 549f02d8ec94d39092ab6d9b103d0d6783a4b024, bfbddeadd4779651403035ee177ae2f22f9f5521, 9907ac9b9a18b92fc34b9e4cb9e10f208dc1d3f7, c97b2a00059608592ad0d86fbb813a4f8cf9464b, d8388614de613c28eeb659c10115060a83739924
LinuxLinux Kernel4.2 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.134; 6.7 up to, but not including, 6.12.81; 6.13 up to, but not including, 6.18.22; 6.19 up to, but not including, 6.19.12; 7.05.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: wifi: wilc1000: fix u8 overflow in SSID scan buffer size calculation The variable valuesize is declared as u8 but accumulates the total length of all SSIDs to scan. Each SSID contributes up to 33 bytes (IEEE80211_MAX_SSID_LEN + 1), and with WILC_MAX_NUM_PROBED_SSID (10) SSIDs the total can reach 330, which wraps around to 74 when stored in a u8. This causes kmalloc to allocate only 75 bytes while the subsequent memcpy writes up to 331 bytes into the buffer, resulting in a 256-byte heap buffer overflow. Widen valuesize from u8 to u32 to accommodate the full range.

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.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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