Linux Kernel Vulnerability in HDLC Protocol Timers

CVE-2026-63803

What is CVE-2026-63803?

This vulnerability in the Linux Kernel affects the HDLC protocol's handling of timer synchronization, specifically involving embedded PPP control protocols. The absence of a proper detach callback in the protocol's implementation results in potential use-after-free conditions when freeing memory related to protocol state. This flaw stems from improper management of timers, where certain cleanup operations do not correctly synchronize active timers before memory deallocation. Affected systems may experience unpredictable behavior, including crashes or potential exploits, if the conditions of this flaw are met. The resolution includes enhancements to timer management, ensuring that all timers are appropriately synchronized before being freed, thereby mitigating the risk of accessing invalid memory.

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