Out-of-bounds Read in Linux

CVE-2025-39943

In the Linux kernel, the following vulnerability has been resolved: ksmbd: smbdirect: validate data_offset and data_length field of smb_direct_data_transfer If data_offset and data_length of smb_direct_data_transfer struct are invalid, out of bounds issue could happen. This patch validate data_offset and data_length field in recv_done.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.4 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H.

EPSS exploit prediction

EPSS: 0.003 (16.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 16th percentile — 16.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-39943: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.000

Affected products

  • Linux — versions 2ea086e35c3d726a3bacd0a971c1f02a50e98206, 5.15, 0
  • Linux Kernel — versions 5.15, 6.17

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-39943?
CVE-2025-39943 is a critical-severity vulnerability in Linux, classified under Out-of-bounds Read. CVSS score: 9.4/10. Published 2025-10-04.
How severe is CVE-2025-39943?
Critical severity. CVSS v3 base score is 9.4 out of 10.
Is CVE-2025-39943 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.