Linux Kernel up to 6.17-rc3 KVM array_index_nospec memory corruption

CVSS Meta Temp Score
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.17-rc3. This vulnerability affects the function array_index_nospec of the component KVM. The manipulation leads to memory corruption. This vulnerability is uniquely identified as CVE-2025-39823. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.17-rc3 and classified as critical. This issue affects the function array_index_nospec of the component KVM. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: use array_index_nospec with indices that come from guest min and dest_id are guest-controlled indices. Using array_index_nospec() after the bounds checks clamps these values to mitigate speculative execution side-channels.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2025-39823 since 04/16/2025. The exploitation is known to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/16/2026).

The vulnerability scanner Nessus provides a plugin with the ID 265253 (Linux Distros Unpatched Vulnerability : CVE-2025-39823), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.298, 5.10.242, 5.15.191, 6.1.150, 6.6.104, 6.12.45, 6.16.5 or 6.17-rc4 eliminates this vulnerability. Applying the patch 72777fc31aa7ab2ce00f44bfa3929c6eabbeaf48/31a0ad2f60cb4816e06218b63e695eb72ce74974/d51e381beed5e2f50f85f49f6c90e023754efa12/33e974c2d5a82b2f9d9ba0ad9cbaabc1c8e3985f/f49161646e03d107ce81a99c6ca5da682fe5fb69/67a05679621b7f721bdba37a5d18665d3aceb695/f57a4bd8d6cb5af05b8ac1be9098e249034639fb/c87bd4dd43a624109c3cc42d843138378a7f4548 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 (265253) and CERT Bund (WID-SEC-2025-2077). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.8
NVD Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 265253
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-39823

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.298/5.10.242/5.15.191/6.1.150/6.6.104/6.12.45/6.16.5/6.17-rc4
Patch: 72777fc31aa7ab2ce00f44bfa3929c6eabbeaf48/31a0ad2f60cb4816e06218b63e695eb72ce74974/d51e381beed5e2f50f85f49f6c90e023754efa12/33e974c2d5a82b2f9d9ba0ad9cbaabc1c8e3985f/f49161646e03d107ce81a99c6ca5da682fe5fb69/67a05679621b7f721bdba37a5d18665d3aceb695/f57a4bd8d6cb5af05b8ac1be9098e249034639fb/c87bd4dd43a624109c3cc42d843138378a7f4548

Timelineinfo

04/16/2025 CVE reserved
09/16/2025 +153 days Advisory disclosed
09/16/2025 +0 days VulDB entry created
01/16/2026 +122 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-39823 (🔒)
GCVE (CVE): GCVE-0-2025-39823
GCVE (VulDB): GCVE-100-324437
CERT Bund: WID-SEC-2025-2077 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 09/16/2025 16:04
Updated: 01/16/2026 22:33
Changes: 09/16/2025 16:04 (59), 09/18/2025 20:54 (2), 10/21/2025 08:55 (7), 12/27/2025 13:43 (1), 01/16/2026 22:33 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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