CVE-2025-39742
Linux Kernel 4.8 – 5.4.297
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2025-39742 is a medium-severity Divide By Zero (CWE-369) vulnerability in Linux Linux Kernel. Its CVSS base score is 5.5 (Medium).
Operationally, ranked at the 6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-2 (Flaw Remediation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-28969
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: RDMA: hfi1: fix possible divide-by-zero in find_hw_thread_mask() The function divides number of online CPUs by num_core_siblings, and later checks the divider by zero. This implies a possibility to get and…
more
divide-by-zero runtime error. Fix it by moving the check prior to division. This also helps to save one indentation level.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the kernel patch that moves the zero check before the division in find_hw_thread_mask().
Requires validation of num_core_siblings (the divisor) prior to the division operation that triggers CWE-369.
Provides structured error handling that could contain the impact of an uncaught divide-by-zero in kernel code.
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 include code analysis, input validation, and testing that prevent divide-by-zero errors.
Vulnerability identification processes can discover divide-by-zero flaws via static analysis or testing.
Routine patching and replacement can remediate divide-by-zero bugs present in deployed software.
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 divide-by-zero conditions before release.
Secure development lifecycle includes input validation and error-handling practices that can prevent divide-by-zero faults.
Application security requirements can mandate checks for zero denominators and safe arithmetic handling.
Secure architecture principles encourage defensive coding patterns that avoid arithmetic exceptions.
Secure coding standards directly require validation to prevent divide-by-zero and similar runtime faults.