{"id":"CVE-2025-21704","state":"PUBLISHED","title":"usb: cdc-acm: Check control transfer buffer size before access","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.","publishedAt":"2025-02-22T09:43:37.377Z","updatedAt":"2026-10-15T01:03:26.561Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"90dd2f1b7342b9a671a5ea4160f408037b92b118","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"871619c2b78fdfe05afb4e8ba548678687beb812","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"7828e9363ac4d23b02419bf2a45b9f1d9fb35646","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6abb510251e75f875797d8983a830e6731fa281c","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"f64079bef6a8a7823358c3f352ea29a617844636","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"383d516a0ebc8641372b521c8cb717f0f1834831","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"e563b01208f4d1f609bcab13333b6c0e24ce6a01","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/class/cdc-acm.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"5.4.291","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.235","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.179","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.129","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.79","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.16","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.4","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/class/cdc-acm.c"]}],"references":["https://git.kernel.org/stable/c/a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2","https://git.kernel.org/stable/c/90dd2f1b7342b9a671a5ea4160f408037b92b118","https://git.kernel.org/stable/c/871619c2b78fdfe05afb4e8ba548678687beb812","https://git.kernel.org/stable/c/7828e9363ac4d23b02419bf2a45b9f1d9fb35646","https://git.kernel.org/stable/c/6abb510251e75f875797d8983a830e6731fa281c","https://git.kernel.org/stable/c/f64079bef6a8a7823358c3f352ea29a617844636","https://git.kernel.org/stable/c/383d516a0ebc8641372b521c8cb717f0f1834831","https://git.kernel.org/stable/c/e563b01208f4d1f609bcab13333b6c0e24ce6a01","https://project-zero.issues.chromium.org/issues/395107243","https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html","https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html","https://cert-portal.siemens.com/productcert/html/ssa-265688.html","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21704.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21704","state":"PUBLISHED","datePublished":"2025-02-22T09:43:37.377Z","dateUpdated":"2026-10-15T01:03:26.561Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.751Z"},"containers":{"cna":{"title":"usb: cdc-acm: Check control transfer buffer size before access","descriptions":[{"lang":"en","value":"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 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