Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/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-2025-21735 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Linux Linux Kernel. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 26th 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-2025-21735 is a vulnerability in the Linux kernel's NFC NCI (Near Field Communication Controller Interface) subsystem, specifically in the nci_hci_create_pipe() function. The issue stems from a lack of bounds checking on a u8 "pipe" variable sourced from the network; values exceeding 127 trigger memory corruption in the caller function, nci_hci_connect_gate(). This out-of-bounds write (CWE-787) affects Linux kernel versions prior to the application of the relevant stable patches and carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
A local attacker with low privileges can exploit this vulnerability by supplying a crafted "pipe" value over an NFC connection, leading to memory corruption. Successful exploitation could allow arbitrary code execution, data tampering, or system crashes, with high impacts on confidentiality, integrity, and availability due to the unbounded write.
Mitigation involves applying kernel patches that add bounds checking to nci_hci_create_pipe(), as detailed in the following stable branch commits: 10b3f947b609713e04022101f492d288a014ddfa, 110b43ef05342d5a11284cc8b21582b698b4ef1c, 172cdfc3a5ea20289c58fb73dadc6fd4a8784a4e, 2ae4bade5a64d126bd18eb66bd419005c5550218, and 59c7ed20217c0939862fbf8145bc49d5b3a13f4f. Security practitioners should update affected Linux kernels promptly, particularly those with NFC functionality enabled.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5189
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: NFC: nci: Add bounds checking in nci_hci_create_pipe() The "pipe" variable is a u8 which comes from the network. If it's more than 127, then it results in memory corruption in…
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the caller, nci_hci_connect_gate().
- 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.