Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-21724 is a high-severity Out-of-bounds Write (CWE-787) 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 9th 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 SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
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-2025-21724 is a shift-out-of-bounds vulnerability in the Linux kernel's iommufd/iova_bitmap subsystem, specifically within the iova_bitmap_offset_to_index() function. The issue arises when shifting the constant "1" (typed as a 32-bit int) by the bitmap->mapped.pgshift value (an unsigned long), which can exceed 31 and trigger undefined behavior due to overflow in the 32-bit type. This is classified under CWE-787 (Out-of-bounds Write) 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 an unchanged security scope (S:U). Successful exploitation enables high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), potentially allowing arbitrary code execution or system disruption within the kernel context.
Mitigation involves applying the upstream kernel patches referenced in the stable repository commits, such as 38ac76fc06bc6826a3e4b12a98efbe98432380a9 and others, which resolve the issue by changing the constant to "1UL" to promote it to unsigned long and match the shift operand's type. Security practitioners should update affected Linux kernels to incorporate these fixes.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5222
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: iommufd/iova_bitmap: Fix shift-out-of-bounds in iova_bitmap_offset_to_index() Resolve a UBSAN shift-out-of-bounds issue in iova_bitmap_offset_to_index() where shifting the constant "1" (of type int) by bitmap->mapped.pgshift (an unsigned long value) could result in undefined…
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behavior. The constant "1" defaults to a 32-bit "int", and when "pgshift" exceeds 31 (e.g., pgshift = 63) the shift operation overflows, as the result cannot be represented in a 32-bit type. To resolve this, the constant is updated to "1UL", promoting it to an unsigned long type to match the operand's type.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and bounds checks) finds out-of-bounds write flaws before deployment.
Requiring documented secure-development standards and tools can mandate bounds-checked coding practices that avoid the weakness.
Input validation can structurally reject or sanitize data that would otherwise trigger an out-of-bounds write.
Memory-protection mechanisms limit the exploitability and blast radius of a successful out-of-bounds write.
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-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.
Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.
Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.
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 and acceptance can detect and prevent out-of-bounds write defects.
Secure development life cycle mandates practices that prevent out-of-bounds writes.
Application security requirements can specify bounds-checking and safe memory handling.
Secure architecture and engineering principles reduce the likelihood of buffer overflows.
Secure coding directly addresses out-of-bounds writes through language choice and coding standards.
Change management can enforce review gates that catch unsafe memory operations before deployment.