Answer in brief
CVE-2025-21704 records a Unknown severity vulnerability in usb: cdc-acm: Check control transfer buffer size before access. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <90dd2f1b7342b9a671a5ea4160f408037b92b118 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <871619c2b78fdfe05afb4e8ba548678687beb812 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7828e9363ac4d23b02419bf2a45b9f1d9fb35646 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6abb510251e75f875797d8983a830e6731fa281c || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f64079bef6a8a7823358c3f352ea29a617844636 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <383d516a0ebc8641372b521c8cb717f0f1834831 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e563b01208f4d1f609bcab13333b6c0e24ce6a01 | a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2, 90dd2f1b7342b9a671a5ea4160f408037b92b118, 871619c2b78fdfe05afb4e8ba548678687beb812, 7828e9363ac4d23b02419bf2a45b9f1d9fb35646, 6abb510251e75f875797d8983a830e6731fa281c, f64079bef6a8a7823358c3f352ea29a617844636, 383d516a0ebc8641372b521c8cb717f0f1834831, e563b01208f4d1f609bcab13333b6c0e24ce6a01 |
| Linux/Linuxgeneric | 2.6.12 | Not reported |
| Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystemgeneric | >=0 <* | * |
Published upstream
Feb 22, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 15, 2026
In the Linux kernel, the following vulnerability has been resolved: usb: cdc-acm: Check control transfer buffer size before access If the first fragment is shorter than struct usb_cdc_notification, we can't calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data, which can lead to memory corruption when the expected_size decreases between fragments, causing `expected_size - acm->nb_index` to wrap. This issue has been present since the beginning of git history; however, it only leads to memory corruption since commit ea2583529cd1 ("cdc-acm: reassemble fragmented notifications"). A mitigating factor is that acm_ctrl_irq() can only execute after userspace has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will do that automatically depending on the USB device's vendor/product IDs and its other interfaces.
Quoted source text, attributed separately from HOL analysis.