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

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proc_get_inode中的释放后重用问题。

CVSS 7.8 · High EPSS 0.23% · P13

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 97a32539b9568bb653683349e5a76d02ff3c3e2c< eda279586e571b05dff44d48e05f8977ad05855d affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< 4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< 966f331403dc3ed04ff64eaf3930cf1267965e53 affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< 63b53198aff2e4e6c5866a4ff73c7891f958ffa4 affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< ede3e8ac90ae106f0b29cd759aadebc1568f1308 affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< 64dc7c68e040251d9ec6e989acb69f8f6ae4a10b affected
97a32539b9568bb653683349e5a76d02ff3c3e2c< 654b33ada4ab5e926cd9c570196fefa7bec7c1df affected
5.6 affected
… +8 more rows
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I. Basic Information for CVE-2025-21999

Vulnerability Information
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Vulnerability Title
proc: fix UAF in proc_get_inode()
Source: CVE Program / CVE List V5
Vulnerability Description
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]
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proc_get_inode中的释放后重用问题。
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 97a32539b9568bb653683349e5a76d02ff3c3e2c ~ eda279586e571b05dff44d48e05f8977ad05855d -
Linux Linux 5.6 -

II. Public POCs for CVE-2025-21999

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III. Intelligence Information for CVE-2025-21999

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Patches & Fixes for CVE-2025-21999 (2)

Same Patch Batch · Linux · 2025-04-03 · 13 CVEs total

CVE-2025-22004 8.6 HIGH net: atm: fix use after free in lec_send()
CVE-2025-22001 7.8 HIGH accel/qaic: Fix integer overflow in qaic_validate_req()
CVE-2025-22007 Bluetooth: Fix error code in chan_alloc_skb_cb()
CVE-2025-22006 net: ethernet: ti: am65-cpsw: Fix NAPI registration sequence
CVE-2025-22005 ipv6: Fix memleak of nhc_pcpu_rth_output in fib_check_nh_v6_gw().
CVE-2025-22003 can: ucan: fix out of bound read in strscpy() source
CVE-2025-22002 netfs: Call `invalidate_cache` only if implemented
CVE-2025-22000 mm/huge_memory: drop beyond-EOF folios with the right number of refs
CVE-2025-21998 firmware: qcom: uefisecapp: fix efivars registration race
CVE-2025-21997 xsk: fix an integer overflow in xp_create_and_assign_umem()
CVE-2025-21996 drm/radeon: fix uninitialized size issue in radeon_vce_cs_parse()
CVE-2025-21995 drm/sched: Fix fence reference count leak

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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