{"cve":"CVE-2021-47338","nvd":{"published":"2024-05-21T15:15:20.610","modified":"2026-08-04T10:16:58.303","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfbmem: Do not delete the mode that is still in use\n\nThe execution of fb_delete_videomode() is not based on the result of the\nprevious fbcon_mode_deleted(). As a result, the mode is directly deleted,\nregardless of whether it is still in use, which may cause UAF.\n\n==================================================================\nBUG: KASAN: use-after-free in fb_mode_is_equal+0x36e/0x5e0 \\\ndrivers/video/fbdev/core/modedb.c:924\nRead of size 4 at addr ffff88807e0ddb1c by task syz-executor.0/18962\n\nCPU: 2 PID: 18962 Comm: syz-executor.0 Not tainted 5.10.45-rc1+ #3\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ...\nCall Trace:\n __dump_stack lib/dump_stack.c:77 [inline]\n dump_stack+0x137/0x1be lib/dump_stack.c:118\n print_address_description+0x6c/0x640 mm/kasan/report.c:385\n __kasan_report mm/kasan/report.c:545 [inline]\n kasan_report+0x13d/0x1e0 mm/kasan/report.c:562\n fb_mode_is_equal+0x36e/0x5e0 drivers/video/fbdev/core/modedb.c:924\n fbcon_mode_deleted+0x16a/0x220 drivers/video/fbdev/core/fbcon.c:2746\n fb_set_var+0x1e1/0xdb0 drivers/video/fbdev/core/fbmem.c:975\n do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108\n vfs_ioctl fs/ioctl.c:48 [inline]\n __do_sys_ioctl fs/ioctl.c:753 [inline]\n __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739\n do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nFreed by task 18960:\n kasan_save_stack mm/kasan/common.c:48 [inline]\n kasan_set_track+0x3d/0x70 mm/kasan/common.c:56\n kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355\n __kasan_slab_free+0x108/0x140 mm/kasan/common.c:422\n slab_free_hook mm/slub.c:1541 [inline]\n slab_free_freelist_hook+0xd6/0x1a0 mm/slub.c:1574\n slab_free mm/slub.c:3139 [inline]\n kfree+0xca/0x3d0 mm/slub.c:4121\n fb_delete_videomode+0x56a/0x820 drivers/video/fbdev/core/modedb.c:1104\n fb_set_var+0x1f3/0xdb0 drivers/video/fbdev/core/fbmem.c:978\n do_fb_ioctl+0x4d9/0x6e0 drivers/video/fbdev/core/fbmem.c:1108\n vfs_ioctl fs/ioctl.c:48 [inline]\n __do_sys_ioctl fs/ioctl.c:753 [inline]\n __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739\n do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46\n entry_SYSCALL_64_after_hwframe+0x44/0xa9","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/087bff9acd2ec6db3f61aceb3224bde90fe0f7f8","https://git.kernel.org/stable/c/0af778269a522c988ef0b4188556aba97fb420cc","https://git.kernel.org/stable/c/359311b85ebec7c07c3a08ae2f3def946cad33fa","https://git.kernel.org/stable/c/d6e76469157d8f240e5dec6f8411aa8d306b1126","https://git.kernel.org/stable/c/f193509afc7ff37a46862610c93b896044d5b693"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47338","score":0.00269,"percentile":0.19143,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}