cbcvebase.
CVE-2025-40271
published 2025-12-06

CVE-2025-40271: 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()…

PriorityP432high7.8
EXPLOIT
EPSS
0.54%
41.5th percentile
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)

Affected

29 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.159-1 (bookworm)linux 6.1.159-1 (bookworm)
debianlinux-6.1< linux 6.1.159-1 (bookworm)linux 6.1.159-1 (bookworm)
linuxlinux
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 1d1596d68a6f11d28f677eedf6cf5b17dbfeb4911d1596d68a6f11d28f677eedf6cf5b17dbfeb491
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < c81d0385500446efe48c305bbb83d47f2ae23a50c81d0385500446efe48c305bbb83d47f2ae23a50
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 4cba73c4c89219beef7685a47374bf88b10223694cba73c4c89219beef7685a47374bf88b1022369
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 6f2482745e510ae1dacc9b090194b9c5f918d7746f2482745e510ae1dacc9b090194b9c5f918d774
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 67272c11f379d9aa5e0f6b16286b9d89b3f7604667272c11f379d9aa5e0f6b16286b9d89b3f76046
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 623bb26127fb581a741e880e1e1a47d79aecb6f8623bb26127fb581a741e880e1e1a47d79aecb6f8
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 03de7ff197a3d0e17d0d5c58fdac99a63cba811003de7ff197a3d0e17d0d5c58fdac99a63cba8110
linuxlinux>= 710585d4922fd315f2cada8fbe550ae8ed23e994 < 895b4c0c79b092d732544011c3cecaf7322c36a1895b4c0c79b092d732544011c3cecaf7322c36a1
linuxlinux_kernel>= 0 < 5.10.247-15.10.247-1
linuxlinux_kernel>= 0 < 6.1.159-16.1.159-1
linuxlinux_kernel>= 0 < 6.12.63-16.12.63-1
linuxlinux_kernel>= 0 < 6.17.9-16.17.9-1
linuxlinux_kernel>= 0 < 5.15.0-173.1835.15.0-173.183
linuxlinux_kernel>= 0 < 6.8.0-106.1066.8.0-106.106
linuxlinux_kernel>= 0 < 6.17.0-14.146.17.0-14.14
linuxlinux_kernel>= 3.19.0 < 5.4.3025.4.302
linuxlinux_kernel>= 5.11.0 < 5.15.1975.15.197
linuxlinux_kernel>= 5.16.0 < 6.1.1596.1.159
linuxlinux_kernel>= 5.5.0 < 5.10.2475.10.247
linuxlinux_kernel>= 6.13.0 < 6.17.96.17.9
linuxlinux_kernel>= 6.2.0 < 6.6.1176.6.117
linuxlinux_kernel>= 6.7.0 < 6.12.596.12.59

CVSS provenance

osv7.8HIGH
vendor_ubuntu7.8HIGH
vendor_redhat7.0MEDIUM
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