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CVE-2025-40271— fs/proc: fix uaf in proc_readdir_de()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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fs proc未正确清理proc_readdir_de中的节点，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.45% · P37

Public Exploits 1

ExploitDB · 1 EDB-52550 [local]

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 710585d4922fd315f2cada8fbe550ae8ed23e994< 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< c81d0385500446efe48c305bbb83d47f2ae23a50 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 4cba73c4c89219beef7685a47374bf88b1022369 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 6f2482745e510ae1dacc9b090194b9c5f918d774 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 67272c11f379d9aa5e0f6b16286b9d89b3f76046 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 623bb26127fb581a741e880e1e1a47d79aecb6f8 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 03de7ff197a3d0e17d0d5c58fdac99a63cba8110 affected
710585d4922fd315f2cada8fbe550ae8ed23e994< 895b4c0c79b092d732544011c3cecaf7322c36a1 affected
… +10 more rows
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I. Basic Information for CVE-2025-40271

Vulnerability Information
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Vulnerability Title
fs/proc: fix uaf in proc_readdir_de()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix uaf in proc_readdir_de() Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access. We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows: 1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3; 2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab; 3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access. CPU 0 | CPU 1 ------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock); [time window] | rb_erase(&root->subdir_node, &parent->subdir); | write_unlock(&proc_subdir_lock); read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF | rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2)
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
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fs proc未正确清理proc_readdir_de中的节点，可能导致释放后重用。
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux 710585d4922fd315f2cada8fbe550ae8ed23e994 ~ 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491 -
Linux Linux 3.19 -

II. Public POCs for CVE-2025-40271

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III. Intelligence Information for CVE-2025-40271

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Same Patch Batch · Linux · 2025-12-06 · 23 CVEs total

CVE-2025-40282 8.8 HIGH Bluetooth: 6lowpan: reset link-local header on ipv6 recv path
CVE-2025-40273 8.8 HIGH NFSD: free copynotify stateid in nfs4_free_ol_stateid()
CVE-2025-40269 7.8 HIGH ALSA: usb-audio: Fix potential overflow of PCM transfer buffer
CVE-2025-40284 7.8 HIGH Bluetooth: MGMT: cancel mesh send timer when hdev removed
CVE-2025-40283 7.8 HIGH Bluetooth: btusb: reorder cleanup in btusb_disconnect to avoid UAF
CVE-2025-40270 7.8 HIGH mm, swap: fix potential UAF issue for VMA readahead
CVE-2025-40280 7.8 HIGH tipc: Fix use-after-free in tipc_mon_reinit_self().
CVE-2025-40272 7.8 HIGH mm/secretmem: fix use-after-free race in fault handler
CVE-2025-40277 7.8 HIGH drm/vmwgfx: Validate command header size against SVGA_CMD_MAX_DATASIZE
CVE-2025-40274 7.8 HIGH KVM: guest_memfd: Remove bindings on memslot deletion when gmem is dying
CVE-2025-40285 7.5 HIGH smb/server: fix possible refcount leak in smb2_sess_setup()
CVE-2025-40276 7.3 HIGH drm/panthor: Flush shmem writes before mapping buffers CPU-uncached
CVE-2025-40278 net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak
CVE-2025-40267 io_uring/rw: ensure allocated iovec gets cleared for early failure
CVE-2025-40268 cifs: client: fix memory leak in smb3_fs_context_parse_param
CVE-2025-40275 ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd
CVE-2025-40289 drm/amdgpu: hide VRAM sysfs attributes on GPUs without VRAM
CVE-2025-40279 net: sched: act_connmark: initialize struct tc_ife to fix kernel leak
CVE-2025-40281 sctp: prevent possible shift-out-of-bounds in sctp_transport_update_rto
CVE-2025-40286 smb/server: fix possible memory leak in smb2_read()

Showing top 20 of 23 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-40271

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