CVE-2025-21704

CVE-2025-21704 is a memory corruption vulnerability in the Linux kernel's USB CDC-ACM driver, specifically affecting the handling of fragmented notifications. This flaw, present since commit ea2583529cd1, can lead to memory corruption if the initial fragment is too short to properly calculate the expected size, causing an integer wrap. Rated with a CVSS score of 7.8 (High), this vulnerability has a local attack vector (AV:L) with low attack complexity (AC:L) and requires low privileges (PR:L). Successful exploitation could result in high impact to confidentiality, integrity, and availability (C:H/I:H/A:H). A mitigating factor is that user interaction is typically required to open /dev/ttyACM*, though ModemManager can automate this. There is no evidence of active exploitation, nor are there known public exploits in Metasploit, Nuclei, or ExploitDB. Despite this, the vulnerability has garnered significant community attention with 3 mentions and 3 media articles, indicating awareness and discussion within the cybersecurity community.