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.

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

EPSS: 0.001 (3.8th percentile) — read the EPSS interpretation.

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.

Affected products

Linux — versions 2ea086e35c3d726a3bacd0a971c1f02a50e98206, 5.15, 0
Linux Linux_kernel — versions 5.15, 6.17

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)

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.