CVE-2026-63990 - Vulnerability Details

Vendors	Products
Linux	Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8
https://git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602
https://git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb
https://git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38
https://git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d
https://git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707
https://git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: bonding: refuse to enslave CAN devices syzbot reported a kernel paging request crash in can_rx_unregister() inside net/can/af_can.c. The crash occurs because a virtual CAN device (vxcan) is being enslaved to a bonding master. During the enslavement process, the bonding driver mutates and modifies the network device states to fit an Ethernet-like aggregation model. However, CAN devices operate on a completely different Layer 2 architecture, relying on the CAN mid-layer private data structure (can_ml_priv) instead of standard Ethernet structures. Since bonding does not initialize or maintain these CAN structures, subsequent operations on the half-enslaved interface (such as closing associated sockets via isotp_release) lead to a null-pointer dereference when accessing the CAN receiver lists. Bonding CAN interfaces is architecturally invalid as CAN lacks MAC addresses, ARP capabilities, and standard Ethernet link-layer mechanisms. While generic loopback devices are blocked globally in net/core/dev.c, virtual CAN devices bypass this check because they do not carry the IFF_LOOPBACK flag, despite acting as local software-loopbacks. Fix this by explicitly blocking network devices of type ARPHRD_CAN from being enslaved at the very beginning of bond_enslave(). This prevents illegal state mutations, eliminates the resulting KASAN crashes, and avoids potential memory leaks from incomplete socket cleanups. As the CAN support has been added a long time after bonding the Fixes-tag points to the introduction of ARPHRD_CAN that would have needed a specific handling in bonding_main.c.
Title		bonding: refuse to enslave CAN devices
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8 https://git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602 https://git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb https://git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38 https://git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d https://git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707 https://git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63990", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.025Z", "datePublished": "2026-07-19T14:56:11.111Z", "dateUpdated": "2026-07-19T14:56:11.111Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-07-19T14:56:11.111Z"}, "descriptions": [{"lang": "en", "value": "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."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/net/bonding/bond_main.c"], "versions": [{"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "69b78b5f3033272e53a2dc2dad675962654a5b38", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "41e8478c4cd896d3abbe33d41afc90c84ac66602", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "f4d78a81f57df82e9d82a2c07471fed1a1235893", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "02f1c87ded33b43d48b4a1d665da15f2157b30d8", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "9ea8a648d9120f7652bcde1ce2c4ad66871af707", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "563090e5d450c665f70d955a39f9587afc7842eb", "status": "affected", "versionType": "git"}, {"version": "cd05acfe65ed2cf2db683fa9a6adb8d35635263b", "lessThan": "8ba68464e4787b6a7ec938826e16124df20fd23d", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/net/bonding/bond_main.c"], "versions": [{"version": "2.6.25", "status": "affected"}, {"version": "0", "lessThan": "2.6.25", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.12", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "5.15.210"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "6.1.176"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "6.6.143"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "6.12.93"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "6.18.35"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "7.0.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.25", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/69b78b5f3033272e53a2dc2dad675962654a5b38"}, {"url": "https://git.kernel.org/stable/c/41e8478c4cd896d3abbe33d41afc90c84ac66602"}, {"url": "https://git.kernel.org/stable/c/f4d78a81f57df82e9d82a2c07471fed1a1235893"}, {"url": "https://git.kernel.org/stable/c/02f1c87ded33b43d48b4a1d665da15f2157b30d8"}, {"url": "https://git.kernel.org/stable/c/9ea8a648d9120f7652bcde1ce2c4ad66871af707"}, {"url": "https://git.kernel.org/stable/c/563090e5d450c665f70d955a39f9587afc7842eb"}, {"url": "https://git.kernel.org/stable/c/8ba68464e4787b6a7ec938826e16124df20fd23d"}], "title": "bonding: refuse to enslave CAN devices", "x_generator": {"engine": "bippy-1.2.0"}}}}

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