Linux kernel macvlan RCU grace period use-after-free in macvlan_common_newlink()
CVE-2026-23273 is a Linux kernel vulnerability in the macvlan networking subsystem caused by a race condition in the error path of macvlan_common_newlink(). The function can make a newly created macvlan device visible to other execution contexts before detecting an error. If link creation then fails, the caller may directly free the associated net_device via free_netdev(dev) without waiting for an RCU grace period. Concurrent packet-processing paths, specifically macvlan_forward_source() as reached from macvlan_handle_frame(), can still hold or obtain references to the device and subsequently dereference freed memory, resulting in a slab use-after-free. The issue was demonstrated with a reproducer using veth interfaces and a macvlan interface in source mode, and KASAN reported the fault in drivers/net/macvlan.c at lines 408 and 444.
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Referenced as one of many CVEs addressed by SUSE kernel security updates; no vulnerability details are provided in the content.
Listed as one of 206 vulnerabilities addressed by a SUSE kernel security update; no per-CVE technical detail is provided in the content.
The content references CVE-2026-23273 in the context of a kernelCTF-related conversation and a Makefile fix, but does not provide substantive details about the vulnerability itself.
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