{"id":"CVE-2026-63990","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbonding: refuse to enslave CAN devices\n\nsyzbot reported a kernel paging request crash in\ncan_rx_unregister() inside net/can/af_can.c","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbonding: refuse to enslave CAN devices\n\nsyzbot reported a kernel paging request crash in\ncan_rx_unregister() inside net/can/af_can.c. The crash occurs\nbecause a virtual…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-401"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.25, < 5.15.210","linux_kernel >= 5.16, < 6.1.176","linux_kernel >= 6.2, < 6.6.143","linux_kernel >= 6.7, < 6.12.93","linux_kernel >= 6.13, < 6.18.35","linux_kernel >= 6.19, < 7.0.12","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.12"],"published":"2026-07-19","updated":"2026-10-07","sourceUpdated":"2026-10-07T20:31:37.400","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63990","references":[{"url":"https://git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00181,"epssPercentile":0.07017,"ingestedAt":"2026-10-07T20:46:46.957Z","slug":"CVE-2026-63990","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbonding: refuse to enslave CAN devices\n\nsyzbot reported a kernel paging request crash in\ncan_rx_unregister() inside net/can/af_can.c. The crash occurs\nbecause a virtual CAN device (vxcan) is being enslaved to a\nbonding master.\n\nDuring the enslavement process, the bonding driver mutates\nand modifies the network device states to fit an Ethernet-like\naggregation model. However, CAN devices operate on a completely\ndifferent Layer 2 architecture, relying on the CAN mid-layer\nprivate data structure (can_ml_priv) instead of standard\nEthernet structures. Since bonding does not initialize or\nmaintain these CAN structures, subsequent operations on the\nhalf-enslaved interface (such as closing associated sockets\nvia isotp_release) lead to a null-pointer dereference when\naccessing the CAN receiver lists.\n\nBonding CAN interfaces is architecturally invalid as CAN lacks\nMAC addresses, ARP capabilities, and standard Ethernet\nlink-layer mechanisms. While generic loopback devices are\nblocked globally in net/core/dev.c, virtual CAN devices\nbypass this check because they do not carry the IFF_LOOPBACK\nflag, despite acting as local software-loopbacks.\n\nFix this by explicitly blocking network devices of type\nARPHRD_CAN from being enslaved at the very beginning of\nbond_enslave(). This prevents illegal state mutations,\neliminates the resulting KASAN crashes, and avoids potential\nmemory leaks from incomplete socket cleanups.\n\nAs the CAN support has been added a long time after bonding\nthe Fixes-tag points to the introduction of ARPHRD_CAN that\nwould have needed a specific handling in bonding_main.c.\n\n## Affected\n\n- `linux_kernel >= 2.6.25, < 5.15.210`\n- `linux_kernel >= 5.16, < 6.1.176`\n- `linux_kernel >= 6.2, < 6.6.143`\n- `linux_kernel >= 6.7, < 6.12.93`\n- `linux_kernel >= 6.13, < 6.18.35`\n- `linux_kernel >= 6.19, < 7.0.12`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.12`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}