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Fencer Vulns
high 8.8

CVE-2025-37899 json

ksmbd: fix use-after-free in session logoff

published 2025-05-20 17 mo ago modified 2026-08-05 3 mo ago also EUVD-2025-15946

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix use-after-free in session logoff

The sess->user object can currently be in use by another thread, for example if another connection has sent a session setup request to bind to the session being free'd. The handler for that connection could be in the smb2_sess_setup function which makes use of sess->user.

Patch / fix

  • Linux Linux 6.1.159, 6.6.119, 6.12.28, 6.14.6, 6.15
  • linux Debian 12 6.1.159-1
  • linux Debian 14, Debian 13 6.12.29-1

debian advisories DEBIAN-CVE-2025-37899

  • linux Ubuntu 24.04 LTS 6.8.0-101.101
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1047.50
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1048.51
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1044.49
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1045.45
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1051.57
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1031.34
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1048.52

ubuntu advisories UBUNTU-CVE-2025-37899

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-37899 updated cvss 4.7

kernel: ksmbd: fix use-after-free in session logoff

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.88% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • sean.heelan.io https://sean.heelan.io/2025/05/22/how-i-used-o3-to-find-cve-2025-37899-a-remote-zeroday-vulnerability-in-the-linux-kernels-smb-implementation/ referenced PoC, tagged "exploit" by a source, unverified
  • news.ycombinator.com https://news.ycombinator.com/item?id=44081338 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.