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CVE-2025-39720

20
FAUCET Score

CVE-2025-39720 is a refcount leak vulnerability in the Linux kernel's ksmbd module, specifically affecting the linux_kernel product. This flaw prevents proper memory deallocation when ksmbd_conn_releasing returns true, leading to resource exhaustion. Rated Medium (CVSS 5.5), it requires local access with low attack complexity and can cause high availability impact. There is currently no public exploit code available, it is not listed in KEV, and while it has garnered some community discussion and media coverage, it is not actively exploited.

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.15, < 6.6.103CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 6.7, < 6.12.44CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 6.13, < 6.16.4CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
6.17CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
6.17CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.5MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.14%
Probability of exploitation in next 30 days
EPSS Percentile
3.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0014 is in the 22nd percentile among its peer group of 15,940 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

microsoftpatch availablevia msrc
Product: 20412-17084Fixed in: 6.6.104.2-1
microsoftpatch availablevia msrc
Product: azl3 kernel 6.6.96.2-2 on Azure Linux 3.0Fixed in: 6.6.104.2-1
ubuntupatch availablevia ubuntu_usn
Product: linux-ibm (noble)Fixed in: 6.8.0-1044.44
ubuntupatch availablevia ubuntu_usn
Product: linux-azure-fips (noble)Fixed in: 6.8.0-1046.52+fips1
ubuntupatch availablevia ubuntu_usn
Product: linux-xilinx (noble)Fixed in: 6.8.0-1023.24
ubuntupatch availablevia ubuntu_usn
Product: linux-azure-6.8 (jammy)Fixed in: 6.8.0-1051.57~22.04.1
ubuntupatch availablevia ubuntu_usn
Product: linux-azure (noble)Fixed in: 6.8.0-1046.52
ubuntupatch availablevia ubuntu_usn
Product: linux-ibm-6.8 (jammy)Fixed in: 6.8.0-1044.44~22.04.1

Vendor Advisories (7)

ubuntuUSN-8126-1

Linux kernel (Azure) vulnerabilities

Mar 25, 2026
ubuntuUSN-8074-2

Linux kernel (Azure FIPS) vulnerabilities

Mar 4, 2026
ubuntuUSN-8074-1

Linux kernel (Azure) vulnerabilities

Mar 4, 2026
ubuntuUSN-8052-2

Linux kernel (Xilinx) vulnerabilities

Feb 24, 2026
ubuntuUSN-8028-8

Linux kernel (IBM) vulnerabilities

Feb 24, 2026
microsoft2025-Sep/CVE-2025-39720Moderate

ksmbd: fix refcount leak causing resource not released

Sep 9, 2025
redhatCVE-2025-39720

kernel: ksmbd: fix refcount leak causing resource not released

Sep 5, 2025

References

git.kernel.org / stable/c/36e010bb865fbaa1202fe9bcce3fd486d6db7606
Patch
git.kernel.org / stable/c/89bb430f621124af39bb31763c4a8b504c9651e2
Patch
git.kernel.org / stable/c/9a7abce6e8c0e2145b346a6d4abf0d9655e9b0e8
Patch
git.kernel.org / stable/c/a1d2bab4d53368a526c97aba92671dd71814f95a
Patch