A newly disclosed zero-day vulnerability in the Linux kernel, tracked as CVE-2026-53264, enables local privilege escalation to root through the net/sched packet scheduling subsystem This article explores vulnerability linux kernel. . It affects the stable tree of the Linux kernel and is a result of a use-after-free condition caused by a lock mismatch in tcf_idr_check_alloc(), which looks up shared traffic control actions by index.
The exploit also depends on specific traffic control components, including the clsact queueing discipline and flower filters, to avoid kernel paths that would otherwise serialize access and make the race condition easier to circumvent. The final exploit utilized multiple binder threads and a deleter thread operating on the same action index to reduce race time from over 15 minutes down to roughly five seconds during testing.
It then reclaimed freed kmalloc-256 objects via user_key_payload allocations triggered through KEYCTL_UPDATE, eventually achieving instruction pointer control and a reliable root escalation chain on CentOS Stream 9 desktop systems. Lee Jia Jie noted that while the method was reliable for the target environment, it still relied on hardcoded ROP gadget offsets, making portability across kernel builds more challenging. Despite Jia Jie’s concerns about AI's limitations, the research indicates that defenders should anticipate faster detection of race conditions, memory safety flaws, and exploit primitives within mature open-source codebases.
