CVE-2026-63797 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution vendors, users of Linux-based systems, security teams responsible for vulnerability management and patching, affected operators, platform administrators, vulnerability management teams, and security teams responsible for monitoring and incident response.

Technical summary

In the Linux kernel, a vulnerability was found in the rpmsg character device driver. Specifically, rpmsg_chrdev_probe() stored a newly allocated eptdev in the default endpoint's priv pointer before calling rpmsg_chrdev_eptdev_add(). If rpmsg_chrdev_eptdev_add() then failed, its error path freed eptdev while the default endpoint may still dispatch callbacks with the stale priv pointer. To fix this, the code was modified to avoid publishing eptdev through the default endpoint until rpmsg_chrdev_eptdev_add() succeeds. Messages received before the priv pointer is published should be ignored by rpmsg_ept_cb(). Flow-control updates can hit rpmsg_ept_flow_cb() in the same window, so both callbacks return success when priv is NULL.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the official patch for the Linux kernel rpmsg character device driver
• Ensure Linux kernel and distribution updates are applied in a timely manner
• Monitor Linux kernel and distribution security advisories
• 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 2026-07-19T12:16:52.190Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the official advisory. The Linux kernel rpmsg character device driver vulnerability allows for a use-after-free issue, which could lead to callbacks being dispatched with a stale pointer. To confirm affected product deployments, assign an owner for follow-up, and review the supplied official advisory or CVE record.

Official resources