{"id":"CVE-2026-63990","summary":"bonding: refuse to enslave CAN devices","details":"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 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.","modified":"2026-07-21T03:47:43.520714460Z","published":"2026-07-19T14:56:11.111Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63990.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602"},{"type":"WEB","url":"https://git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63990.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63990"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cd05acfe65ed2cf2db683fa9a6adb8d35635263b"},{"fixed":"69b78b5f3033272e53a2dc2dad675962654a5b38"},{"fixed":"41e8478c4cd896d3abbe33d41afc90c84ac66602"},{"fixed":"f4d78a81f57df82e9d82a2c07471fed1a1235893"},{"fixed":"02f1c87ded33b43d48b4a1d665da15f2157b30d8"},{"fixed":"9ea8a648d9120f7652bcde1ce2c4ad66871af707"},{"fixed":"563090e5d450c665f70d955a39f9587afc7842eb"},{"fixed":"8ba68464e4787b6a7ec938826e16124df20fd23d"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-63990.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.25"},{"fixed":"5.15.210"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.176"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.143"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.93"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.35"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.12"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-63990.json"}}],"schema_version":"1.7.5"}