{"cve":"CVE-2025-39866","nvd":{"published":"2025-09-19T16:15:45.657","modified":"2026-10-19T21:10:00.160","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs: writeback: fix use-after-free in __mark_inode_dirty()\n\nAn use-after-free issue occurred when __mark_inode_dirty() get the\nbdi_writeback that was in the progress of switching.\n\nCPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1\n......\npstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\npc : __mark_inode_dirty+0x124/0x418\nlr : __mark_inode_dirty+0x118/0x418\nsp : ffffffc08c9dbbc0\n........\nCall trace:\n __mark_inode_dirty+0x124/0x418\n generic_update_time+0x4c/0x60\n file_modified+0xcc/0xd0\n ext4_buffered_write_iter+0x58/0x124\n ext4_file_write_iter+0x54/0x704\n vfs_write+0x1c0/0x308\n ksys_write+0x74/0x10c\n __arm64_sys_write+0x1c/0x28\n invoke_syscall+0x48/0x114\n el0_svc_common.constprop.0+0xc0/0xe0\n do_el0_svc+0x1c/0x28\n el0_svc+0x40/0xe4\n el0t_64_sync_handler+0x120/0x12c\n el0t_64_sync+0x194/0x198\n\nRoot cause is:\n\nsystemd-random-seed                         kworker\n----------------------------------------------------------------------\n___mark_inode_dirty                     inode_switch_wbs_work_fn\n\n  spin_lock(&inode->i_lock);\n  inode_attach_wb\n  locked_inode_to_wb_and_lock_list\n     get inode->i_wb\n     spin_unlock(&inode->i_lock);\n     spin_lock(&wb->list_lock)\n  spin_lock(&inode->i_lock)\n  inode_io_list_move_locked\n  spin_unlock(&wb->list_lock)\n  spin_unlock(&inode->i_lock)\n                                    spin_lock(&old_wb->list_lock)\n                                      inode_do_switch_wbs\n                                        spin_lock(&inode->i_lock)\n                                        inode->i_wb = new_wb\n                                        spin_unlock(&inode->i_lock)\n                                    spin_unlock(&old_wb->list_lock)\n                                    wb_put_many(old_wb, nr_switched)\n                                      cgwb_release\n                                      old wb released\n  wb_wakeup_delayed() accesses wb,\n  then trigger the use-after-free\n  issue\n\nFix this race condition by holding inode spinlock until\nwb_wakeup_delayed() finished.","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/1edc2feb9c759a9883dfe81cb5ed231412d8b2e4","https://git.kernel.org/stable/c/b187c976111960e6e54a6b1fff724f6e3d39406c","https://git.kernel.org/stable/c/bf89b1f87c72df79cf76203f71fbf8349cd5c9de","https://git.kernel.org/stable/c/c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a","https://git.kernel.org/stable/c/d02d2c98d25793902f65803ab853b592c7a96b29"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-39866","score":0.00314,"percentile":0.24087,"date":"2026-10-25"},"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."]}