Critical 9.8Published Dec 8, 2025

CVE-2025-40320smb: client: fix potential cfid UAF in smb2_query_info_compound

Updated under an hour ago (2026-10-19 07:50 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential cfid UAF in smb2_query_info_compound When smb2_query_info_compound() retries, a previously allocated cfid may have been freed in the first attempt. Because cfid wasn't reset on replay, later cleanup could act on a stale pointer, leading to a potential use-after-free. Reinitialize cfid to NULL under the replay label. Example trace (trimmed): refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 11224 at ../lib/refcount.c:28 refcount_warn_saturate+0x9c/0x110 [...] RIP: 0010:refcount_warn_saturate+0x9c/0x110 [...] Call Trace: <TASK> smb2_query_info_compound+0x29c/0x5c0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? step_into+0x10d/0x690 ? __legitimize_path+0x28/0x60 smb2_queryfs+0x6a/0xf0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] smb311_queryfs+0x12d/0x140 [cifs f90b72658819bd21c94769b6a652029a07a7172f] ? kmem_cache_alloc+0x18a/0x340 ? getname_flags+0x46/0x1e0 cifs_statfs+0x9f/0x2b0 [cifs f90b72658819bd21c94769b6a652029a07a7172f] statfs_by_dentry+0x67/0x90 vfs_statfs+0x16/0xd0 user_statfs+0x54/0xa0 __do_sys_statfs+0x20/0x50 do_syscall_64+0x58/0x80

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/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: Oct 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	433042a91f9373241307725b52de573933ffedbf builds before 939c4e33005e2a56ea8fcedddf0da92df864bd3b; from 4f1fffa2376922f3d1d506e49c0fd445b023a28e before 327f89c21601ebb7889f8c97754b76f08ce95a0c; from 4f1fffa2376922f3d1d506e49c0fd445b023a28e before b556c278d43f4707a9073ca74d55581b4f279806; from 4f1fffa2376922f3d1d506e49c0fd445b023a28e before 5c76f9961c170552c1d07c830b5e145475151600; from 6.6.32 before 6.6.117	CNA record

References

https://git.kernel.org/stable/c/939c4e33005e2a56ea8fcedddf0da92df864bd3b
https://git.kernel.org/stable/c/327f89c21601ebb7889f8c97754b76f08ce95a0c
https://git.kernel.org/stable/c/b556c278d43f4707a9073ca74d55581b4f279806
https://git.kernel.org/stable/c/5c76f9961c170552c1d07c830b5e145475151600

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.