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medium 4.3

CVE-2025-9640 json

Samba: vfs_streams_xattr uninitialized memory write possible

published last yr. modified 3d ago also EUVD-2025-34611

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

A flaw was found in Samba, in the vfs_streams_xattr module, where uninitialized heap memory could be written into alternate data streams. This allows an authenticated user to read residual memory content that may include sensitive data, resulting in an information disclosure vulnerability.

Patch / fix

  • samba.org samba 4.21.5, 4.21.9, 4.23.2
  • samba Debian 12 2:4.17.12+dfsg-0+deb12u3
  • samba Debian 13 2:4.22.6+dfsg-0+deb13u1
  • samba Debian 14 2:4.23.2+dfsg-1

debian advisories DEBIAN-CVE-2025-9640

  • samba Ubuntu 22.04 LTS 2:4.15.13+dfsg-0ubuntu1.10
  • samba Ubuntu 24.04 LTS 2:4.19.5+dfsg-4ubuntu9.4
  • samba Ubuntu 25.10 2:4.22.3+dfsg-4ubuntu2.1
  • samba Ubuntu Pro 14.04 LTS 2:4.3.11+dfsg-0ubuntu0.14.04.20+esm15
  • samba Ubuntu Pro 16.04 LTS 2:4.3.11+dfsg-0ubuntu0.16.04.34+esm4
  • samba Ubuntu Pro 18.04 LTS 2:4.7.6+dfsg~ubuntu-0ubuntu2.29+esm3
  • samba Ubuntu Pro 20.04 LTS 2:4.15.13+dfsg-0ubuntu0.20.04.8+esm1

ubuntu advisories UBUNTU-CVE-2025-9640

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

  • samba SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 4.22.5+git.431.dc5a539f124-160000.1.1
  • samba SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +3 more 4.15.13+git.736.b791be993ba-150300.3.96.1
  • samba SLE Module for Basesystem 15 SP7, SLE High Availability Extension 15 SP7 4.21.8+git.418.e80c9b2a88c-150700.3.11.2
  • samba SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +6 more 4.15.13+git.736.b791be993ba-150400.3.40.1
  • samba SLE Module for Basesystem 15 SP6, SLE High Availability Extension 15 SP6, openSUSE Leap 15.6 4.19.8+git.435.78ced6cf30d-150600.3.21.1
  • samba SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS, SLE High Availability Extension 12 SP5 4.15.13+git.664.e8416d8d213-3.99.1
  • samba SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Micro 5.5 +3 more 4.17.12+git.510.0efaadf376b-150500.3.34.1

suse advisories SUSE-SU-2025:21005-1SUSE-SU-2025:21026-1SUSE-SU-2025:3677-1SUSE-SU-2025:3676-1SUSE-SU-2025:03618-1SUSE-SU-2025:03612-1

  • samba openSUSE Leap 16.0 4.22.5+git.431.dc5a539f124-160000.1.1
  • samba openSUSE Tumbleweed 4.22.5+git.431.dc5a539f124-1.1

opensuse advisories openSUSE-SU-2025:20048-1openSUSE-SU-2025:15649-1

  • samba Alpine 3.24, Alpine 3.23, Alpine 3.22 4.21.9-r0

alpine advisories ALPINE-CVE-2025-9640

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2025-9640 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2025-9640 updated cvss 4.3

samba: vfs_streams_xattr uninitialized memory write possible

  • Red Hat Enterprise Linux 6 samba, samba4, samba4-dc, samba-swat, samba4-libs, samba4-pidl, +17 more Red Hat Enterprise Linux 7 ctdb, samba, samba-dc, ctdb-tests, samba-libs, samba-pidl, +18 more Red Hat Enterprise Linux 8 ctdb, samba, libnetapi, ctdb-tests, samba-libs, samba-pidl, +24 more Red Hat Enterprise Linux 9 ctdb, samba, libldb, ldb-tools, libnetapi, samba-libs, +27 more Red Hat Enterprise Linux 10 samba Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected products

  • samba.org samba
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat OpenShift Container Platform 4

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource

References

Sources

Fencer Intel 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.