{"cve":"CVE-2025-21704","nvd":{"published":"2025-02-22T10:15:11.263","modified":"2026-10-15T02:17:28.313","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: cdc-acm: Check control transfer buffer size before access\n\nIf the first fragment is shorter than struct usb_cdc_notification, we can't\ncalculate an expected_size. Log an error and discard the notification\ninstead of reading lengths from memory outside the received data, which can\nlead to memory corruption when the expected_size decreases between\nfragments, causing `expected_size - acm->nb_index` to wrap.\n\nThis issue has been present since the beginning of git history; however,\nit only leads to memory corruption since commit ea2583529cd1\n(\"cdc-acm: reassemble fragmented notifications\").\n\nA mitigating factor is that acm_ctrl_irq() can only execute after userspace\nhas opened /dev/ttyACM*; but if ModemManager is running, ModemManager will\ndo that automatically depending on the USB device's vendor/product IDs and\nits other interfaces.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-787"],"references":["https://git.kernel.org/stable/c/383d516a0ebc8641372b521c8cb717f0f1834831","https://git.kernel.org/stable/c/6abb510251e75f875797d8983a830e6731fa281c","https://git.kernel.org/stable/c/7828e9363ac4d23b02419bf2a45b9f1d9fb35646","https://git.kernel.org/stable/c/871619c2b78fdfe05afb4e8ba548678687beb812","https://git.kernel.org/stable/c/90dd2f1b7342b9a671a5ea4160f408037b92b118"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2025-21704","score":0.00368,"percentile":0.30421,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}