High 7.8Published Apr 3, 2025

CVE-2025-21999proc: fix UAF in proc_get_inode()

Updated under an hour ago (2026-10-19 08:00 UTC)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: proc: fix UAF in proc_get_inode() Fix race between rmmod and /proc/XXX's inode instantiation. The bug is that pde->proc_ops don't belong to /proc, it belongs to a module, therefore dereferencing it after /proc entry has been registered is a bug unless use_pde/unuse_pde() pair has been used. use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops never changes so information necessary for inode instantiation can be saved _before_ proc_register() in PDE itself and used later, avoiding pde->proc_ops->... dereference. rmmod lookup sys_delete_module proc_lookup_de pde_get(de); proc_get_inode(dir->i_sb, de); mod->exit() proc_remove remove_proc_subtree proc_entry_rundown(de); free_module(mod); if (S_ISREG(inode->i_mode)) if (de->proc_ops->proc_read_iter) --> As module is already freed, will trigger UAF BUG: unable to handle page fault for address: fffffbfff80a702b PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:proc_get_inode+0x302/0x6e0 RSP: 0018:ffff88811c837998 EFLAGS: 00010a06 RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007 RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158 RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20 R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0 R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001 FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> proc_lookup_de+0x11f/0x2e0 __lookup_slow+0x188/0x350 walk_component+0x2ab/0x4f0 path_lookupat+0x120/0x660 filename_lookup+0x1ce/0x560 vfs_statx+0xac/0x150 __do_sys_newstat+0x96/0x110 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e [adobriyan@gmail.com: don't do 2 atomic ops on the common path]

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): CWE-416
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: Modified
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 97a32539b9568bb653683349e5a76d02ff3c3e2c before eda279586e571b05dff44d48e05f8977ad05855d; 97a32539b9568bb653683349e5a76d02ff3c3e2c builds before 4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa; from 97a32539b9568bb653683349e5a76d02ff3c3e2c before 966f331403dc3ed04ff64eaf3930cf1267965e53; 97a32539b9568bb653683349e5a76d02ff3c3e2c builds before 63b53198aff2e4e6c5866a4ff73c7891f958ffa4; from 97a32539b9568bb653683349e5a76d02ff3c3e2c before ede3e8ac90ae106f0b29cd759aadebc1568f1308; 97a32539b9568bb653683349e5a76d02ff3c3e2c builds before 64dc7c68e040251d9ec6e989acb69f8f6ae4a10b; from 97a32539b9568bb653683349e5a76d02ff3c3e2c before 654b33ada4ab5e926cd9c570196fefa7bec7c1df	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 2.6.23 before 6.1.132; from 6.2 before 6.6.85; from 6.7 before 6.12.21; from 6.13 before 6.13.9; 6.14; 6.14; 6.14; 6.14	NVD

References

https://git.kernel.org/stable/c/eda279586e571b05dff44d48e05f8977ad05855d
https://git.kernel.org/stable/c/4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa
https://git.kernel.org/stable/c/966f331403dc3ed04ff64eaf3930cf1267965e53patch
https://git.kernel.org/stable/c/63b53198aff2e4e6c5866a4ff73c7891f958ffa4patch
https://git.kernel.org/stable/c/ede3e8ac90ae106f0b29cd759aadebc1568f1308patch
https://git.kernel.org/stable/c/64dc7c68e040251d9ec6e989acb69f8f6ae4a10bpatch
https://git.kernel.org/stable/c/654b33ada4ab5e926cd9c570196fefa7bec7c1dfpatch
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.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.