{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31446", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.091Z", "datePublished": "2026-04-22T13:53:42.751Z", "dateUpdated": "2026-08-05T12:22:36.689Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:22:36.689Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix use-after-free in update_super_work when racing with umount\n\nCommit b98535d09179 (\"ext4: fix bug_on in start_this_handle during umount\nfilesystem\") moved ext4_unregister_sysfs() before flushing s_sb_upd_work\nto prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups\nreads during unmount. However, this introduced a use-after-free because\nupdate_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which\naccesses the kobject's kernfs_node after it has been freed by kobject_del()\nin ext4_unregister_sysfs():\n\n update_super_work ext4_put_super\n ----------------- --------------\n ext4_unregister_sysfs(sb)\n kobject_del(&sbi->s_kobj)\n __kobject_del()\n sysfs_remove_dir()\n kobj->sd = NULL\n sysfs_put(sd)\n kernfs_put() // RCU free\n ext4_notify_error_sysfs(sbi)\n sysfs_notify(&sbi->s_kobj)\n kn = kobj->sd // stale pointer\n kernfs_get(kn) // UAF on freed kernfs_node\n ext4_journal_destroy()\n flush_work(&sbi->s_sb_upd_work)\n\nInstead of reordering the teardown sequence, fix this by making\next4_notify_error_sysfs() detect that sysfs has already been torn down\nby checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call\nin that case. A dedicated mutex (s_error_notify_mutex) serializes\next4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs()\nto prevent TOCTOU races where the kobject could be deleted between the\nstate_in_sysfs check and the sysfs_notify() call." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable ext4 paths are reached through local filesystem operations such as mounting/unmounting an ext4 image, reading ext4 procfs state, or writing ext4 sysfs controls; there is no direct network packet path.\nAC:L - The race is between queued ext4 superblock error work and teardown, and a crafted/ext4-error scenario can repeatedly drive the work while unmount/cleanup proceeds; under the required rule, this attacker-influenced race is Low complexity.\nPR:N - Directly initiating mount/umount or sysfs error injection requires CAP_SYS_ADMIN in the initial namespace, but a highest-severity reasonable scenario is an attacker-supplied crafted ext4 filesystem image mounted/unmounted by a victim or privileged automounter, requiring no attacker privilege.\nUI:R - Exploitation in the no-attacker-privilege scenario requires a victim or privileged system component to mount and later unmount/process the malicious ext4 filesystem image.\nS:U - The corruption occurs inside the kernel filesystem/sysfs/kernfs lifetime management for the same host kernel security authority; it is not a VM escape or cross-authority boundary break.\nC:H - The bug is a use-after-free of a kernfs_node reached through sysfs_notify after kobject deletion, and kernel UAFs are treated as capable of enabling high-impact information disclosure.\nI:H - The stale kernfs_node is refcounted and used after free, giving a memory-corruption primitive that is defensibly treated as potentially exploitable for kernel control-flow or data modification.\nA:H - At minimum the UAF can crash or oops the kernel during ext4 unmount/error-work processing, causing high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/ext4.h", "fs/ext4/super.c", "fs/ext4/sysfs.c" ], "versions": [ { "version": "52c3a04f9ec2a16a4204d6274db338cb8d5b2d74", "lessThan": "c8fe17a1b308c3d8c703ebfb049b325f844342c3", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "c4d829737329f2290dd41e290b7d75effdb2a7ff", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "9449f99ba04f5dd1c8423ad8a90b3651d7240d1d", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "034053378dd81837fd6c7a43b37ee2e58d4f0b4e", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "c97e282f7bfd0c3554c63d289964a5ca6a1d2ffe", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "08b10e6f37fc533a759e9833af0692242e8b3f93", "status": "affected", "versionType": "git" }, { "version": "b98535d091795a79336f520b0708457aacf55c67", "lessThan": "d15e4b0a418537aafa56b2cb80d44add83e83697", "status": "affected", "versionType": "git" }, { "version": "585ef03c9e79672781f954daae730dfe24bf3a46", "status": "affected", "versionType": "git" }, { "version": "afe490e48d47df1b3f64012835c1bc2f075a8c8b", "status": "affected", "versionType": "git" }, { "version": "5.15.38", "lessThan": "5.15.203", "status": "affected", "versionType": "semver" }, { "version": "5.10.114", "lessThan": "5.11", "status": "affected", "versionType": "semver" }, { "version": "5.17.6", "lessThan": "5.18", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/ext4.h", "fs/ext4/super.c", "fs/ext4/sysfs.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.168", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.131", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.80", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.21", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.11", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "5.15.38", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.1.168" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.6.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.12.80" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.18.21" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.19.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "7.0" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.114" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17.6" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c8fe17a1b308c3d8c703ebfb049b325f844342c3" }, { "url": "https://git.kernel.org/stable/c/c4d829737329f2290dd41e290b7d75effdb2a7ff" }, { "url": "https://git.kernel.org/stable/c/9449f99ba04f5dd1c8423ad8a90b3651d7240d1d" }, { "url": "https://git.kernel.org/stable/c/034053378dd81837fd6c7a43b37ee2e58d4f0b4e" }, { "url": "https://git.kernel.org/stable/c/c97e282f7bfd0c3554c63d289964a5ca6a1d2ffe" }, { "url": "https://git.kernel.org/stable/c/08b10e6f37fc533a759e9833af0692242e8b3f93" }, { "url": "https://git.kernel.org/stable/c/d15e4b0a418537aafa56b2cb80d44add83e83697" } ], "title": "ext4: fix use-after-free in update_super_work when racing with umount", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:47:51.536Z" }, "affected": [ { "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", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { 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