Linux Kernel up to 6.18.39/7.1.4 fwctl lib/string_helpers.c cxlctl_get_supported_features buffer overflow

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.
8.7	$5k-$25k	0.00

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.18.39/7.1.4. Impacted is the function cxlctl_get_supported_features of the file lib/string_helpers.c of the component fwctl. This manipulation causes buffer overflow. This vulnerability is tracked as CVE-2026-80640. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.18.39/7.1.4. Affected by this vulnerability is the function cxlctl_get_supported_features of the file lib/string_helpers.c of the component fwctl. The manipulation with an unknown input leads to a buffer overflow vulnerability. The CWE definition for the vulnerability is CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: cxl/fwctl: Fix __fortify_panic Fix a runtime assertion in cxlctl_get_supported_features(). Fortify complains that it is potentially overflowing the entries array per __counted_by_le(num_entries). Quiet the false positive by initializing @num_entries earlier. memcpy: detected buffer overflow: 48 byte write of buffer size 0 WARNING: lib/string_helpers.c:1036 at __fortify_report+0x4d/0xa0, CPU#7: fwctl/1398 RIP: 0010:__fortify_report+0x50/0xa0 Call Trace: __fortify_panic+0xd/0xf cxlctl_get_supported_features.cold+0x23/0x35 [cxl_core]

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-80640 since 08/26/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are required for exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/28/2026).

Upgrading to version 6.18.40 or 7.1.5 eliminates this vulnerability. Applying the patch b8d15e85596ad8993d42e0703a9741961a2f03eb/18c67ecc5dafe14055edcea53f36f4e31df1816b/6c9d2e87df40d606f1c85143e9acb1ecff463d5e is able to eliminate this problem.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

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: 9.1
VulDB Meta Temp Score: 8.7

VulDB Base Score: 9.1
VulDB Temp Score: 8.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

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: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.40/7.1.5
Patch: b8d15e85596ad8993d42e0703a9741961a2f03eb/18c67ecc5dafe14055edcea53f36f4e31df1816b/6c9d2e87df40d606f1c85143e9acb1ecff463d5e

Timelineinfo

08/26/2026 CVE reserved
08/28/2026 +2 days Advisory disclosed
08/28/2026 +0 days VulDB entry created
08/28/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-80640 (🔒)
GCVE (CVE): GCVE-0-2026-80640
GCVE (VulDB): GCVE-100-396577

Entryinfo

Created: 08/28/2026 10:31
Changes: 08/28/2026 10:31 (60)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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