High severity · published May 1, 2026
CVE-2026-31708
smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
8.1
CVSS
0.4%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
smb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL
and the default QUERY_INFO path. The QUERY_INFO branch clamps
qi.input_buffer_length to the server-reported OutputBufferLength and then
copies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but
it never verifies that the flexible-array payload actually fits within
rsp_iov[1].iov_len.
A malicious server can return OutputBufferLength larger than the actual
QUERY_INFO response, causing copy_to_user() to walk past the response
buffer and expose adjacent kernel heap to userspace.
Guard the QUERY_INFO copy with a bounds check on the actual Buffer
payload. Use struct_size(qi_rsp, Buffer, qi.input_buffer_length)
rather than an open-coded addition so the guard cannot overflow on
32-bit builds.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 29% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.1 before 6.6.136; 6.7 before 6.12.84; 6.13 before 6.18.25; 6.19 before 7.0.2 · source: NVD
LI
Linux · Linux
f5778c398713692a16150ae96e5c8270bab8399f before e66bdc0704977ecee667a81d38255b579c2353d0; f5778c398713692a16150ae96e5c8270bab8399f before 9e203dbb5402897c43130fb171a2617008a91f45; f5778c398713692a16150ae96e5c8270bab8399f before 1dd757379997b71a328a4b591ffaf481acd0ead1; f5778c398713692a16150ae96e5c8270bab8399f before a34d456934fe42e4da5d2cc07787bf418bee99c6; f5778c398713692a16150ae96e5c8270bab8399f before ac2f14e4705d020f04e806efa0d49ab8dc2b145f; f5778c398713692a16150ae96e5c8270bab8399f before 078fae8f50adebb903ccf2252b44391324571e78; +3 more · source: vendor
SS
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem · Siemens
0 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-31708
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-31708
Patch
https://git.kernel.org/stable/c/078fae8f50adebb903ccf2252b44391324571e78
git.kernel.org
https://git.kernel.org/stable/c/1dd757379997b71a328a4b591ffaf481acd0ead1
Patch
https://git.kernel.org/stable/c/85fd46ee26a11841c670449508025965f61ce131
git.kernel.org
https://git.kernel.org/stable/c/9e203dbb5402897c43130fb171a2617008a91f45
Patch
https://git.kernel.org/stable/c/a34d456934fe42e4da5d2cc07787bf418bee99c6
Patch
https://git.kernel.org/stable/c/a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e
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