Linux Kernel up to 6.17-rc2 netfilter include/linux/skbuff.h reference count

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.0	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 6.17-rc2. This issue affects some unknown processing in the library include/linux/skbuff.h of the component netfilter. Executing a manipulation can lead to reference count. This vulnerability is handled as CVE-2025-38732. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.17-rc2. This vulnerability affects an unknown functionality in the library include/linux/skbuff.h of the component netfilter. The manipulation with an unknown input leads to a reference count vulnerability. The CWE definition for the vulnerability is CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_reject: don't leak dst refcount for loopback packets recent patches to add a WARN() when replacing skb dst entry found an old bug: WARNING: include/linux/skbuff.h:1165 skb_dst_check_unset include/linux/skbuff.h:1164 [inline] WARNING: include/linux/skbuff.h:1165 skb_dst_set include/linux/skbuff.h:1210 [inline] WARNING: include/linux/skbuff.h:1165 nf_reject_fill_skb_dst+0x2a4/0x330 net/ipv4/netfilter/nf_reject_ipv4.c:234 [..] Call Trace: nf_send_unreach+0x17b/0x6e0 net/ipv4/netfilter/nf_reject_ipv4.c:325 nft_reject_inet_eval+0x4bc/0x690 net/netfilter/nft_reject_inet.c:27 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] .. This is because blamed commit forgot about loopback packets. Such packets already have a dst_entry attached, even at PRE_ROUTING stage. Instead of checking hook just check if the skb already has a route attached to it.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2025-38732 since 04/16/2025. The exploitation appears to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 261640 (Linux Distros Unpatched Vulnerability : CVE-2025-38732), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.241, 5.15.190, 6.1.149, 6.6.103, 6.12.44, 6.16.4 or 6.17-rc3 eliminates this vulnerability. Applying the patch 7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8/82ef97abf22790182f7d433c74960dfd61b99c33/b7a885ba25960c91db237c3f83b4285156789bce/a0a3ace2a57887dac1e7c9a724846040c3e31868/51e8531371f90bee742c63775c9a568e5d6bf3c5/b32e1590a8d22cf7d7f965e46d5576051acf8e42/91a79b792204313153e1bdbbe5acbfc28903b3a5 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (261640), EUVD (EUVD-2025-31557) and CERT Bund (WID-SEC-2025-1988). Once again VulDB remains the best source for vulnerability data.

Affected

• Debian Linux
• Google Cloud Platform
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• NetApp FAS
• NetApp AFF
• NetApp ActiveIQ Unified Manager
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Microsoft Azure
• Dell Secure Connect Gateway
• IBM QRadar SIEM
• IBM Security Verify Access
• Dell NetWorker

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.240
• 5.15.189
• 6.1.148
• 6.6.102
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.16.0
• 6.16.1
• 6.16.2
• 6.16.3
• 6.17-rc1
• 6.17-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Reference count
CWE: CWE-911 / CWE-664
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 261640
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-38732

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.241/5.15.190/6.1.149/6.6.103/6.12.44/6.16.4/6.17-rc3
Patch: 7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8/82ef97abf22790182f7d433c74960dfd61b99c33/b7a885ba25960c91db237c3f83b4285156789bce/a0a3ace2a57887dac1e7c9a724846040c3e31868/51e8531371f90bee742c63775c9a568e5d6bf3c5/b32e1590a8d22cf7d7f965e46d5576051acf8e42/91a79b792204313153e1bdbbe5acbfc28903b3a5

Timelineinfo

04/16/2025 CVE reserved
09/05/2025 +142 days Advisory disclosed
09/05/2025 +0 days VulDB entry created
02/09/2026 +157 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38732 (🔒)
GCVE (CVE): GCVE-0-2025-38732
GCVE (VulDB): GCVE-100-322876
EUVD: 🔒
CERT Bund: WID-SEC-2025-1988 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 09/05/2025 21:40
Updated: 02/09/2026 11:22
Changes: 09/05/2025 21:40 (59), 09/07/2025 05:14 (2), 09/09/2025 06:17 (7), 11/06/2025 14:34 (1), 11/25/2025 15:05 (1), 11/27/2025 13:57 (1), 12/29/2025 11:03 (1), 01/05/2026 10:09 (1), 01/09/2026 23:23 (11), 01/11/2026 02:39 (1), 01/26/2026 11:25 (1), 02/09/2026 11:22 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

Discussion

Do you need the next level of professionalism?

Upgrade your account now!