CVE-2025-71143
Linux Kernel 6.6.1 – 6.6.120
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2025-71143 is a high-severity Improper Validation of Array Index (CWE-129) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-71143 is an array-index-out-of-bounds vulnerability in the Linux kernel's Samsung Exynos clock output driver, specifically in the exynos_clkout_probe() function within drivers/clk/samsung/clk-exynos-clkout.c. The issue arises because the .num field in struct clk_hw_onecell_data is assigned after the .hws[] array has been accessed, leading to a UBSAN_BOUNDS warning on index 0 access when the array count is still zero. This stems from a prior commit annotating .hws with __counted_by, which enforces bounds checking. The vulnerability is classified under CWE-129 (Improper Validation of Array Index) with a CVSS v3.1 base score of 7.8.
A local attacker with low privileges (PR:L) can exploit this vulnerability with low attack complexity (AC:L) and no user interaction (UI:N), in a local attack vector (AV:L) with unchanged scope (S:U). Successful exploitation could result in high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), potentially allowing arbitrary code execution or system compromise within the kernel context where the driver is loaded.
Mitigation involves applying the upstream kernel patches referenced in the stable git commits, such as a317f63255ebc3dac378c79c5bff4f8d0561c290, cf33f0b7df13685234ccea7be7bfe316b60db4db, eb1f3a6ab3efee2b52361879cdc2dc6b11f499c0, and fbf57f5e453dadadb3d29b2d1dbe067e3dc4e236. These patches reorder the initialization to assign .num before any .hws[] access, resolving the bounds violation. Security practitioners should update affected Linux kernels, particularly those using Samsung Exynos hardware, to the patched versions.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2480
Vulnerability Data
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…
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(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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and bounds checking that prevent improper array indexing.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect out-of-bounds array access but does not prevent the weakness by itself.
Secure development lifecycle mandates input validation and bounds checking that directly prevents improper array indexing.
Application security requirements include validation of untrusted input used for indexing or addressing memory structures.
Secure architecture principles encourage defensive coding patterns that reduce index-related vulnerabilities.
Secure coding standards explicitly require bounds checking and validation of array indices derived from untrusted data.