VDB-322896 · CVE-2025-39686 · Nessus 261653

Linux Kernel up to 6.17-rc2 comedi insn_rw_emulate_bits information disclosure

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5.6	$0-$5k	0.00

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.17-rc2. This affects the function insn_rw_emulate_bits of the component comedi. The manipulation results in information disclosure. This vulnerability is identified as CVE-2025-39686. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 6.17-rc2. Affected is the function insn_rw_emulate_bits of the component comedi. The manipulation with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: comedi: Make insn_rw_emulate_bits() do insn->n samples The `insn_rw_emulate_bits()` function is used as a default handler for `INSN_READ` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_READ`. Similarly, it is used as a default handler for `INSN_WRITE` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_WRITE`. It works by emulating the `INSN_READ` or `INSN_WRITE` instruction handling with a constructed `INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE` instructions are supposed to be able read or write multiple samples, indicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently only handles a single sample. For `INSN_READ`, the comedi core will copy `insn->n` samples back to user-space. (That triggered KASAN kernel-infoleak errors when `insn->n` was greater than 1, but that is being fixed more generally elsewhere in the comedi core.) Make `insn_rw_emulate_bits()` either handle `insn->n` samples, or return an error, to conform to the general expectation for `INSN_READ` and `INSN_WRITE` handlers.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2025-39686 since 04/16/2025. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1592.

The vulnerability scanner Nessus provides a plugin with the ID 261653 (Linux Distros Unpatched Vulnerability : CVE-2025-39686), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 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 ab77e85bd3bc006ef40738f26f446a660813da44/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b/842f307a1d115b24f2bcb2415c4e344f11f55930/92352ed2f9ac422181e381c2430c2d0dfb46faa0/dc0a2f142d655700db43de90cb6abf141b73d908/7afba9221f70d4cbce0f417c558879cba0eb5e66 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 (261653) and CERT Bund (WID-SEC-2025-1988). VulDB is the best source for vulnerability data and more expert information about this specific topic.

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

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: 5.6
VulDB Meta Temp Score: 5.6

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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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: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒