CVE-2025-21704

usb: cdc-acm: Check control transfer buffer size before access

Published Feb 22, 2025 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4102-1 linux-6.1 security update
Debian DLA Debian DLA DLA-4178-1 linux security update
EUVD EUVD EUVD-2025-4440 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.
Ubuntu USN Ubuntu USN USN-7510-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-4 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-5 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-6 Linux kernel (AWS FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-7 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-8 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-2 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-3 Linux kernel (GKE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7512-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-2 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-4 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-5 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-6 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-7 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-8 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-9 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-2 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-3 Linux kernel (BlueField) vulnerabilities
Ubuntu USN Ubuntu USN USN-7518-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7539-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7540-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7593-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7602-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7640-1 Linux kernel (IoT) vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-3 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7719-1 Linux kernel (Raspberry Pi Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7737-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8070-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8070-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8070-3 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8112-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8112-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8112-3 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8112-4 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8112-5 Linux kernel (Azure) vulnerabilities
History
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-787
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 4.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
Metrics threat_severity

Low

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-130
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low

Type Values Removed Values Added
Description 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.
Title usb: cdc-acm: Check control transfer buffer size before access
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 15, 2026, 1:03 AM
Reserved
Dec 29, 2024, 8:45 AM
Status
Modified
Published
Feb 22, 2025, 10:15 AM
Modified
Oct 15, 2026, 2:17 AM
Severity
Moderate
Public date
Feb 22, 2025, 12:00 AM