CVE-2025-38523

Advisory lineage Upstream: 0 Downstream: 9
Analyzed
Published: 16 Aug 2025, 11:12
Last modified:11 May 2026, 21:29

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

16 Aug 2025, 11:12
Published
Vulnerability first disclosed
11 May 2026, 21:29
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix the smbd_response slab to allow usercopy The handling of received data in the smbdirect client code involves using copy_to_iter() to copy data from the smbd_reponse struct's packet trailer to a folioq buffer provided by netfslib that encapsulates a chunk of pagecache. If, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks then performed in copy_to_iter() oopsing with something like the following: CIFS: Attempting to mount //172.31.9.1/test CIFS: VFS: RDMA transport established usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102! ... RIP: 0010:usercopy_abort+0x6c/0x80 ... Call Trace: <TASK> __check_heap_object+0xe3/0x120 __check_object_size+0x4dc/0x6d0 smbd_recv+0x77f/0xfe0 [cifs] cifs_readv_from_socket+0x276/0x8f0 [cifs] cifs_read_from_socket+0xcd/0x120 [cifs] cifs_demultiplex_thread+0x7e9/0x2d50 [cifs] kthread+0x396/0x830 ret_from_fork+0x2b8/0x3b0 ret_from_fork_asm+0x1a/0x30 The problem is that the smbd_response slab's packet field isn't marked as being permitted for usercopy. Fix this by passing parameters to kmem_slab_create() to indicate that copy_to_iter() is permitted from the packet region of the smbd_response slab objects, less the header space.

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.02%• Percentile: 5%

Techniques & Countermeasures

  • CWE-1188•Initialization of a Resource with an Insecure Default

    The product initializes or sets a resource with a default that is intended to be changed by the product's installer, administrator, or maintainer, but the default is not secure.

Affected Systems

  • linux•linux

    ≥ ee4cdf7ba857a894ad1650d6ab77669cbbfa329e, < 87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4 | ≥ ee4cdf7ba857a894ad1650d6ab77669cbbfa329e, < f0dd353d47f7051afa98c6c60c7486831eb1a410 | ≥ ee4cdf7ba857a894ad1650d6ab77669cbbfa329e, < 43e7e284fc77b710d899569360ea46fa3374ae22 | 6.12

  • linux•linux_kernel

    ≥ 6.12, < 6.12.36 | ≥ 6.13, < 6.15.8 | 6.16:rc1 | 6.16:rc2 | 6.16:rc3

References (3)