CVE-2026-63960 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, and users of Linux-based systems that utilize the usb: typec: wcove driver. Additionally, security teams and vulnerability management teams should also be aware of this issue and review their systems for potential exposure.

Technical summary

The wcove_read_rx_buffer() function in the Linux kernel's usb: typec: wcove driver did not properly validate the number of bytes received from the port partner. The function used a 5-bit field (USBC_RXINFO_RXBYTES) to determine the number of bytes to read into a struct pd_message, which is 30 bytes in size. A malicious port partner could transmit a 31-byte frame, causing the loop to write past the destination buffer. Furthermore, the function used regmap_read() to read into an unsigned int *, which stored four bytes at the destination address. Passing a byte pointer (msg + i) caused each iteration to write four bytes, with high bytes being zeroed out. The issue was addressed by limiting the loop to the size of the destination buffer and reading each register into a local variable before storing only the low byte.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the Linux kernel patch to update the usb: typec: wcove driver.
• Verify that the Linux kernel version used in your system has the patch applied.
• Monitor Linux kernel updates and apply patches promptly.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record was published on 2026-07-19T16:17:14.897Z and has not been modified since then. The NVD entry is currently Received. The issue was addressed by limiting the loop to the size of the destination buffer and reading each register into a local variable before storing only the low byte. Linux kernel developers should verify that the patch has been applied to their systems and review the official advisory for affected scope and severity.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.