CVE-2026-53223
HighCVSS 7.1Exploitation Probability (EPSS)
Low risk3th percentile — higher than 3% of all known CVEs
Summary
A vulnerability in the Linux kernel's timestamp cmsg handling for AF_PACKET sockets was found. The incorrect assumption that the PACKET_OUTGOING flag uniquely identifies error queue packets allows reading AF_PACKET control buffer state as sock_exterr_skb, potentially leading to memory disclosure or kernel panic.
Risk Assessment
The organization risks leakage of sensitive kernel memory data (e.g., passwords, keys) or system crash (kernel panic) by sending a crafted packet with timestamping enabled and SO_RXQ_OVFL option.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit: net: guard timestamp cmsgs to real error queue skbs). If an update is not possible, consider disabling the SO_RXQ_OVFL option for AF_PACKET sockets.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net: guard timestamp cmsgs to real error queue skbs skb_is_err_queue() treats PACKET_OUTGOING as the sole marker for an skb from sk_error_queue. That assumption is not true for AF_PACKET sockets: outgoing packet taps are also delivered to packet sockets with skb->pkt_type == PACKET_OUTGOING, but their skb->cb is owned by AF_PACKET instead of struct sock_exterr_skb. If such an skb is received with timestamping enabled, the generic timestamp cmsg path can read AF_PACKET control-buffer state as sock_exterr_skb::opt_stats. With SO_RXQ_OVFL enabled, the packet drop counter overlaps opt_stats. An odd drop count makes the path emit SCM_TIMESTAMPING_OPT_STATS with skb->len and skb->data. For non-linear skbs this copies past the linear head and can trigger hardened usercopy or disclose adjacent heap contents. Keep skb_is_err_queue() local to net/socket.c, but make it verify that the PACKET_OUTGOING marker is paired with the sock_rmem_free destructor installed by sock_queue_err_skb(). AF_PACKET receive skbs use normal receive ownership and no longer pass as error-queue skbs, while legitimate sk_error_queue entries keep the PACKET_OUTGOING marker and sock_rmem_free ownership.