{"id":"CVE-2026-74615","summary":"vxlan: do not arm the ageing timer on a device that is down","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: do not arm the ageing timer on a device that is down\n\nvxlan_changelink() arms vxlan-\u003eage_timer whenever the requested ageing\ninterval differs from the configured one:\n\n\tif (conf.age_interval != vxlan-\u003ecfg.age_interval)\n\t\tmod_timer(&vxlan-\u003eage_timer, jiffies);\n\nThere is no netif_running() test, so the timer is armed even on a device\nthat was never brought up.  The only synchronous cancel in the driver is\nthe timer_delete_sync() in vxlan_stop(), which is .ndo_stop.\nnetif_close_many() drops devices without IFF_UP before\n__dev_close_many() runs, so that cancel is skipped for such a device.\n\nvxlan_setup() sets dev-\u003eneeds_free_netdev = true and age_timer is a\nmember of struct vxlan_dev, so free_netdev() releases the allocation the\ntimer lives in while it is still queued on a timer_base.\nexpire_timers() unlinks the entry before it loads timer-\u003efunction, so\nthe timer core writes through the freed object's list pointers:\n\n  BUG: KASAN: slab-use-after-free in __run_timers+0x208/0x654\n  Write of size 8 at addr ffff00001adace68 by task true/192\n   __asan_store8+0x84/0xac\n   __run_timers+0x208/0x654\n   run_timer_softirq+0x154/0x18c\n  Allocated by task 189:\n   alloc_netdev_mqs+0x64/0x720\n   rtnl_create_link+0x4ac/0x520\n   rtnl_newlink+0x758/0xd00\n  Freed by task 191:\n   netdev_release+0x40/0x58\n   netdev_run_todo+0x4a4/0x8c0\n   rtnl_dellink+0x200/0x4e8\n\nThe rtnl operations involved are netns-scoped, so an unprivileged user\ncan perform them in a new user and network namespace.\n\nArming the timer on a down device never had an effect: vxlan_cleanup()\nreturns early on !netif_running(), and vxlan_open() arms the timer for\nany non-zero interval once the device is brought up.  Add the missing\ntest.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e","modified":"2026-08-27T11:31:00.187360428Z","published":"2026-08-22T15:32:00.588Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74615.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/26c179d47403d2f919ee914cc02c31d896b59fee"},{"type":"WEB","url":"https://git.kernel.org/stable/c/46bb297ad77680e009244f067f27d51cf5b8c7cf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/619dd29045e439d0b0f8c6d4fec1af447a050680"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6b095e99b9e67ea31f0c4b00260e010898253519"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6b4119af544996a545cf84b16f1dbce829ba0de8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9dc561f0522c35bdd66e0646a748814a138ec4ca"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b37971686ec59fb027fa4910ba16805e68fddb97"},{"type":"WEB","url":"https://git.kernel.org/stable/c/be44d79d14d7f9ae7c8ffb7272142005341b5123"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74615.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74615"},{"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":"40051c4dcad5b374156ad9cceae8d15c0ef1cb95"},{"fixed":"be44d79d14d7f9ae7c8ffb7272142005341b5123"},{"fixed":"26c179d47403d2f919ee914cc02c31d896b59fee"},{"fixed":"9dc561f0522c35bdd66e0646a748814a138ec4ca"},{"fixed":"619dd29045e439d0b0f8c6d4fec1af447a050680"},{"fixed":"6b095e99b9e67ea31f0c4b00260e010898253519"},{"fixed":"46bb297ad77680e009244f067f27d51cf5b8c7cf"},{"fixed":"6b4119af544996a545cf84b16f1dbce829ba0de8"},{"fixed":"b37971686ec59fb027fa4910ba16805e68fddb97"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74615.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.152"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.104"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74615.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}