CVE-2025-68288
Description
In the Linux kernel, the following vulnerability has been resolved:
usb: storage: Fix memory leak in USB bulk transport
A kernel memory leak was identified by the 'ioctl_sg01' test from Linux Test Project (LTP). The following bytes were mainly observed: 0x53425355.
When USB storage devices incorrectly skip the data phase with status data, the code extracts/validates the CSW from the sg buffer, but fails to clear it afterwards. This leaves status protocol data in srb's transfer buffer, such as the US_BULK_CS_SIGN 'USBS' signature observed here. Thus, this can lead to USB protocols leaks to user space through SCSI generic (/dev/sg*) interfaces, such as the one seen here when the LTP test requested 512 KiB.
Fix the leak by zeroing the CSW data in srb's transfer buffer immediately after the validation of devices that skip data phase.
Note: Differently from CVE-2018-1000204, which fixed a big leak by zero- ing pages at allocation time, this leak occurs after allocation, when USB protocol data is written to already-allocated sg pages.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A memory leak in the Linux kernel's USB storage driver leaks USB protocol data (including the 'USBS' signature) to user space via SCSI generic interfaces.
Vulnerability
A memory leak in the Linux kernel's USB mass storage driver occurs during USB bulk transport. When a USB storage device incorrectly skips the data phase and provides status data, the driver extracts and validates the Command Status Wrapper (CSW) from the scatter-gather (sg) buffer but fails to clear it afterward. This leaves residual protocol data, such as the US_BULK_CS_SIGN ('USBS') signature, in the srb's transfer buffer [1].
Exploitation
The vulnerability is triggered through the SCSI generic (/dev/sg*) interface, which allows user-space programs to send SCSI commands. An attacker with access to a USB storage device that can cause the driver to skip the data phase can exploit this. The Linux Test Project (LTP) test 'ioctl_sg01' demonstrated the leak when requesting 512 KiB of data [1]. No authentication is required beyond the ability to interact with the USB device.
Impact
An attacker can leak USB protocol data, including the 'USBS' signature, to user space. This information disclosure could aid in further attacks by revealing details about the USB storage protocol handling. The leak is distinct from CVE-2018-1000204, which addressed a similar issue by zeroing pages at allocation time; here, the data is written to already-allocated sg pages [1].
Mitigation
The fix has been applied in the Linux kernel stable tree. The commit zeroes the CSW data in srb's transfer buffer immediately after validation when the device skips the data phase [1]. Users should update their kernel to include this patch.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
7- git.kernel.org/stable/c/0f18eac44c5668204bf6eebb01ddb369ac56932bnvd
- git.kernel.org/stable/c/41e99fe2005182139b1058db71f0d241f8f0078cnvd
- git.kernel.org/stable/c/467fec3cefbeb9e3ea80f457da9a5666a71ca0d0nvd
- git.kernel.org/stable/c/4ba515dfff7eeca369ab85cdbb3f3b231c71720cnvd
- git.kernel.org/stable/c/5b815ddb3f5560fac35b16de3a2a22d5f81c5993nvd
- git.kernel.org/stable/c/83f0241959831586d9b6d47f6bd5d3dec8f43bf0nvd
- git.kernel.org/stable/c/cb1401b5bcc2feb5b038fc4b512e5968b016e05envd
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