CVE-2025-21704
Linux Kernel buffer overflow
- Published22 Feb 2025
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- 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
- https://git.kernel.org/stable/c/a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2
References
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
- 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
- https://git.kernel.org/stable/c/a4e1ae5c0533964170197e4fb4f33bc8c1db5cd2
- https://git.kernel.org/stable/c/e563b01208f4d1f609bcab13333b6c0e24ce6a01
- https://git.kernel.org/stable/c/f64079bef6a8a7823358c3f352ea29a617844636
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
and 2 more references
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2025-21704 being actively exploited?
CVE-2025-21704 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.36%.
How severe is CVE-2025-21704?
CVE-2025-21704 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 0.36% probability of exploitation.
Which products are affected by CVE-2025-21704?
Affected products include Linux Kernel.
How do I fix CVE-2025-21704?
Upgrade affected software to a fixed version, for example Linux Kernel 5.4.291 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2025-21704 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.