{"id":"CVE-2021-47082","title":"In the Linux kernel, the following vulnerability has been resolved:\n\ntun: avoid double free in tun_free_netdev\n\nAvoid double free in tun_free_netdev() by moving the\ndev->tstats and tun->security allocs to a new ndo_init routine\n(tun_net_…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntun: avoid double free in tun_free_netdev\n\nAvoid double free in tun_free_netdev() by moving the\ndev->tstats and tun->security allocs to a new ndo_init routine\n(tun_net_…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-415"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel < 4.19.280","linux_kernel >= 4.20, < 5.4.240","linux_kernel >= 5.5, < 5.10.136","linux_kernel >= 5.11, < 5.15.12","linux_kernel = 5.16"],"patched":["linux_kernel 5.15.12"],"published":"2024-03-04","updated":"2026-08-04","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-47082","references":[{"url":"https://git.kernel.org/stable/c/0c0e566f0387490d16f166808c72e9c772027681","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/158b515f703e75e7d68289bf4d98c664e1d632df","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8eb43d635950e27c29f1e9e49a23b31637f37757","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a01a4e9f5dc93335c716fa4023b1901956e8c904","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/0c0e566f0387490d16f166808c72e9c772027681","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/158b515f703e75e7d68289bf4d98c664e1d632df","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/8eb43d635950e27c29f1e9e49a23b31637f37757","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/a01a4e9f5dc93335c716fa4023b1901956e8c904","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00252,"epssPercentile":0.16904,"ingestedAt":"2026-08-05T05:58:02.375Z","slug":"CVE-2021-47082","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntun: avoid double free in tun_free_netdev\n\nAvoid double free in tun_free_netdev() by moving the\ndev->tstats and tun->security allocs to a new ndo_init routine\n(tun_net_init()) that will be called by register_netdevice().\nndo_init is paired with the desctructor (tun_free_netdev()),\nso if there's an error in register_netdevice() the destructor\nwill handle the frees.\n\nBUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605\n\nCPU: 0 PID: 25750 Comm: syz-executor416 Not tainted 5.16.0-rc2-syzk #1\nHardware name: Red Hat KVM, BIOS\nCall Trace:\n<TASK>\n__dump_stack lib/dump_stack.c:88 [inline]\ndump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106\nprint_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247\nkasan_report_invalid_free+0x55/0x80 mm/kasan/report.c:372\n____kasan_slab_free mm/kasan/common.c:346 [inline]\n__kasan_slab_free+0x107/0x120 mm/kasan/common.c:374\nkasan_slab_free include/linux/kasan.h:235 [inline]\nslab_free_hook mm/slub.c:1723 [inline]\nslab_free_freelist_hook mm/slub.c:1749 [inline]\nslab_free mm/slub.c:3513 [inline]\nkfree+0xac/0x2d0 mm/slub.c:4561\nselinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605\nsecurity_tun_dev_free_security+0x4f/0x90 security/security.c:2342\ntun_free_netdev+0xe6/0x150 drivers/net/tun.c:2215\nnetdev_run_todo+0x4df/0x840 net/core/dev.c:10627\nrtnl_unlock+0x13/0x20 net/core/rtnetlink.c:112\n__tun_chr_ioctl+0x80c/0x2870 drivers/net/tun.c:3302\ntun_chr_ioctl+0x2f/0x40 drivers/net/tun.c:3311\nvfs_ioctl fs/ioctl.c:51 [inline]\n__do_sys_ioctl fs/ioctl.c:874 [inline]\n__se_sys_ioctl fs/ioctl.c:860 [inline]\n__x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860\ndo_syscall_x64 arch/x86/entry/common.c:50 [inline]\ndo_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80\nentry_SYSCALL_64_after_hwframe+0x44/0xae\n\n## Affected\n\n- `linux_kernel < 4.19.280`\n- `linux_kernel >= 4.20, < 5.4.240`\n- `linux_kernel >= 5.5, < 5.10.136`\n- `linux_kernel >= 5.11, < 5.15.12`\n- `linux_kernel = 5.16`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.15.12`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}