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CVE-2026-31446— ext4: fix use-after-free in update_super_work when racing with umount

CVSS 7.8 · High EPSS 0.01% · P2
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I. Basic Information for CVE-2026-31446

Vulnerability Information
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Vulnerability Title
ext4: fix use-after-free in update_super_work when racing with umount
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于update_super_work函数在卸载时存在释放后重用，可能导致访问已释放的kernfs_node。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
LinuxLinux 52c3a04f9ec2a16a4204d6274db338cb8d5b2d74 ~ c8fe17a1b308c3d8c703ebfb049b325f844342c3 -
LinuxLinux 5.18 -

II. Public POCs for CVE-2026-31446

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III. Intelligence Information for CVE-2026-31446

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-314639.8 CRITICALiomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-314369.8 CRITICALdmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-314449.8 CRITICALksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-314789.8 CRITICALksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
CVE-2026-315019.8 CRITICALnet: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-314489.4 CRITICALext4: avoid infinite loops caused by residual data
CVE-2026-314328.8 HIGHksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-314338.8 HIGHksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-314358.8 HIGHnetfs: Fix read abandonment during retry
CVE-2026-314508.8 HIGHext4: publish jinode after initialization
CVE-2026-314768.2 HIGHksmbd: do not expire session on binding failure
CVE-2026-314648.1 HIGHscsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-315138.1 HIGHBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-314907.8 HIGHdrm/xe/pf: Fix use-after-free in migration restore
CVE-2026-314797.8 HIGHdrm/xe: always keep track of remap prev/next
CVE-2026-314947.8 HIGHnet: macb: use the current queue number for stats
CVE-2026-315027.8 HIGHteam: fix header_ops type confusion with non-Ethernet ports
CVE-2026-314497.8 HIGHext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-315047.8 HIGHnet: fix fanout UAF in packet_release() via NETDEV_UP race
CVE-2026-315057.8 HIGHiavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

Showing top 20 of 100 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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