{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39866", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.143Z", "datePublished": "2025-09-19T15:26:35.725Z", "dateUpdated": "2026-08-05T12:05:45.584Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:05:45.584Z" }, "descriptions": [ { "lang": "en", "value": "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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached from an ordinary write(2) syscall (vfs_write → ext4_buffered_write_iter → file_modified → generic_update_time → __mark_inode_dirty), and the competing side requires local cgroup/writeback activity. No network protocol handler is involved.\nAC:L - The attacker drives both sides of the race — a multi-threaded write() loop dirties the inode while the attacker forces cgroup writeback switches by dirtying the file from a second memcg and tearing that cgroup down, making the old wb's last reference drop. Attempts are unlimited and the bug was observed occurring spontaneously during normal boot, and CONFIG_CGROUP_WRITEBACK is default-y on all mainstream kernels.\nPR:L - Only an unprivileged local account with write access to a file on a writeback-capable filesystem (ext4/xfs home or /tmp) is needed; cgroup manipulation used to widen the race is available to ordinary users through systemd's delegated per-user cgroup subtree.\nUI:N - The attacker triggers everything itself through its own write() syscalls and cgroup activity; no victim action or interaction is required.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed bdi_writeback is dereferenced as `wb->bdi->capabilities`, so a re-sprayed object yields an attacker-controlled pointer dereference and an arbitrary kernel-memory read primitive, enabling disclosure of arbitrary kernel data.\nI:H - wb_wakeup_delayed() writes into the freed object (spin_lock_irq on wb->work_lock) and inserts the freed `wb->dwork` timer into the timer wheel, giving list-write primitives and an attacker-controlled `timer->function` — a direct control-flow hijack path to arbitrary kernel code execution.\nA:H - The use-after-free reliably produces a kernel oops/panic as reported in the original crash trace (__mark_inode_dirty+0x124), and can be triggered repeatedly to crash the system." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fs-writeback.c" ], "versions": [ { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "e2a14bbae5d8bacaa301362744a110e2be40a3a3", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "b187c976111960e6e54a6b1fff724f6e3d39406c", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "1edc2feb9c759a9883dfe81cb5ed231412d8b2e4", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "bf89b1f87c72df79cf76203f71fbf8349cd5c9de", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "e63052921f1b25a836feb1500b841bff7a4a0456", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a", "status": "affected", "versionType": "git" }, { "version": "0747259d13febfcc838980a63c414c9b920cea6f", "lessThan": "d02d2c98d25793902f65803ab853b592c7a96b29", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fs-writeback.c" ], "versions": [ { "version": "4.2", "status": "affected" }, { "version": "0", "lessThan": "4.2", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.247", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.192", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.151", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.105", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.46", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.6", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "4.2", "versionEndExcluding": "5.10.247" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "5.15.192" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "6.1.151" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "6.6.105" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "6.12.46" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "6.16.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e2a14bbae5d8bacaa301362744a110e2be40a3a3" }, { "url": "https://git.kernel.org/stable/c/b187c976111960e6e54a6b1fff724f6e3d39406c" }, { "url": "https://git.kernel.org/stable/c/1edc2feb9c759a9883dfe81cb5ed231412d8b2e4" }, { "url": "https://git.kernel.org/stable/c/bf89b1f87c72df79cf76203f71fbf8349cd5c9de" }, { "url": "https://git.kernel.org/stable/c/e63052921f1b25a836feb1500b841bff7a4a0456" }, { "url": "https://git.kernel.org/stable/c/c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a" }, { "url": "https://git.kernel.org/stable/c/d02d2c98d25793902f65803ab853b592c7a96b29" } ], "title": "fs: writeback: fix use-after-free in __mark_inode_dirty()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:44:17.299Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:43:02.443Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC CN 4100", "versions": [ { "status": "affected", "version": "0", "lessThan": "V5.0", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", 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