CyberSecBulletin
CVE-2025-71143NVD status: Analyzed

Linux: Improper Validation of Array Index

Published Updated By the CyberSecBulletin desk

CVE-2025-71143 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 fbf57f5e453dadadb3d29b2d1dbe067e3dc4e236, eb1f3a6ab3efee2b52361879cdc2dc6b11f499c0, a317f63255ebc3dac378c79c5bff4f8d0561c290 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 fbf57f5e453dadadb3d29b2d1dbe067e3dc4e236 or eb1f3a6ab3efee2b52361879cdc2dc6b11f499c0 or a317f63255ebc3dac378c79c5bff4f8d0561c290 or cf33f0b7df13685234ccea7be7bfe316b60db4db, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.120 or 6.12.64 or 6.18.4, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxf316cdff8d677db9ad9c90acb44c4cd535b0ee27 up to, but not including, fbf57f5e453dadadb3d29b2d1dbe067e3dc4e236; f316cdff8d677db9ad9c90acb44c4cd535b0ee27 up to, but not including, eb1f3a6ab3efee2b52361879cdc2dc6b11f499c0; f316cdff8d677db9ad9c90acb44c4cd535b0ee27 up to, but not including, a317f63255ebc3dac378c79c5bff4f8d0561c290; f316cdff8d677db9ad9c90acb44c4cd535b0ee27 up to, but not including, cf33f0b7df13685234ccea7be7bfe316b60db4db; 6.6fbf57f5e453dadadb3d29b2d1dbe067e3dc4e236, eb1f3a6ab3efee2b52361879cdc2dc6b11f499c0, a317f63255ebc3dac378c79c5bff4f8d0561c290, cf33f0b7df13685234ccea7be7bfe316b60db4db
LinuxLinux Kernel6.6.1 up to, but not including, 6.6.120; 6.7 up to, but not including, 6.12.64; 6.13 up to, but not including, 6.18.4; 6.6; 6.196.6.120, 6.12.64, 6.18.4

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
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: clk: samsung: exynos-clkout: Assign .num before accessing .hws Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by") annotated the hws member of 'struct clk_hw_onecell_data' with __counted_by, which informs the bounds sanitizer (UBSAN_BOUNDS) about the number of elements in .hws[], so that it can warn when .hws[] is accessed out of bounds. As noted in that change, the __counted_by member must be initialized with the number of elements before the first array access happens, otherwise there will be a warning from each access prior to the initialization because the number of elements is zero. This occurs in exynos_clkout_probe() due to .num being assigned after .hws[] has been accessed: UBSAN: array-index-out-of-bounds in drivers/clk/samsung/clk-exynos-clkout.c:178:18 index 0 is out of range for type 'clk_hw *[*]' Move the .num initialization to before the first access of .hws[], clearing up the warning.

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

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

References

Recent Improper Validation of Array Index vulnerabilities

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