Subject: [ASA-201808-4] linux: denial of service Arch Linux Security Advisory ASA-201808-4 ========================================= Severity: High Date : 2018-08-08 CVE-ID : CVE-2018-5390 Package : linux Type : denial of service Remote : Yes Link : https://security.archlinux.org/AVG-747 Summary ======= The package linux before version 4.17.11-1 is vulnerable to denial of service. Resolution ========== Upgrade to 4.17.11-1. # pacman -Syu "linux>=4.17.11-1" The problem has been fixed upstream in version 4.17.11. Workaround ========== None. Description =========== A flaw named SegmentSmack was found in the way the Linux kernel handled specially crafted TCP packets. A remote attacker could use this flaw to trigger time and calculation expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() functions by sending specially modified packets within ongoing TCP sessions which could lead to a CPU saturation and hence a denial of service on the system. Maintaining the denial of service condition requires continuous two-way TCP sessions to a reachable open port, thus the attacks cannot be performed using spoofed IP addresses. Impact ====== A remote attacker is able to saturate the CPU and hence cause a denial of service on the host system by sending specially modified packets within ongoing TCP sessions. References ========== https://www.kb.cert.org/vuls/id/962459 https://www.spinics.net/lists/netdev/msg514742.html https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=72cd43ba64fc172a443410ce01645895850844c8 https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f4a3313d8e2ca9fd8d8f45e40a2903ba782607e7 https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3d4bf93ac12003f9b8e1e2de37fe27983deebdcf https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8541b21e781a22dce52a74fef0b9bed00404a1cd https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=58152ecbbcc6a0ce7fddd5bf5f6ee535834ece0c https://security.archlinux.org/CVE-2018-5390