CVE-2025-40271fs/proc: fix uaf in proc_readdir_de()
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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)
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Deferred
- Record last updated
- Aug 5, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491; from 710585d4922fd315f2cada8fbe550ae8ed23e994 before c81d0385500446efe48c305bbb83d47f2ae23a50; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 4cba73c4c89219beef7685a47374bf88b1022369; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 6f2482745e510ae1dacc9b090194b9c5f918d774; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 67272c11f379d9aa5e0f6b16286b9d89b3f76046; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 623bb26127fb581a741e880e1e1a47d79aecb6f8; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 03de7ff197a3d0e17d0d5c58fdac99a63cba8110; 710585d4922fd315f2cada8fbe550ae8ed23e994 builds before 895b4c0c79b092d732544011c3cecaf7322c36a1 | CNA record |
Siemens RUGGEDCOM RST2428P siemens:ruggedcom_rst2428p (from the name) | before V4.0 | CISA ADP |
References
- https://git.kernel.org/stable/c/1d1596d68a6f11d28f677eedf6cf5b17dbfeb491
- https://git.kernel.org/stable/c/c81d0385500446efe48c305bbb83d47f2ae23a50
- https://git.kernel.org/stable/c/4cba73c4c89219beef7685a47374bf88b1022369
- https://git.kernel.org/stable/c/6f2482745e510ae1dacc9b090194b9c5f918d774
- https://git.kernel.org/stable/c/67272c11f379d9aa5e0f6b16286b9d89b3f76046
- https://git.kernel.org/stable/c/623bb26127fb581a741e880e1e1a47d79aecb6f8
- https://git.kernel.org/stable/c/03de7ff197a3d0e17d0d5c58fdac99a63cba8110
- https://git.kernel.org/stable/c/895b4c0c79b092d732544011c3cecaf7322c36a1
- https://cert-portal.siemens.com/productcert/html/ssa-253495.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.