Linux Kernel up to 6.6.102/6.12.42/6.15.10/6.16.1 loop fs/buffer.c __getblk_slow buffer overflow

CVSS Meta Temp Score
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CTI Interest Score
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6.6$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 6.6.102/6.12.42/6.15.10/6.16.1. The affected element is the function __getblk_slow of the file fs/buffer.c of the component loop. Executing a manipulation can lead to buffer overflow. This vulnerability is registered as CVE-2025-38709. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.6.102/6.12.42/6.15.10/6.16.1. This vulnerability affects the function __getblk_slow of the file fs/buffer.c of the component loop. 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. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: loop: Avoid updating block size under exclusive owner Syzbot came up with a reproducer where a loop device block size is changed underneath a mounted filesystem. This causes a mismatch between the block device block size and the block size stored in the superblock causing confusion in various places such as fs/buffer.c. The particular issue triggered by syzbot was a warning in __getblk_slow() due to requested buffer size not matching block device block size. Fix the problem by getting exclusive hold of the loop device to change its block size. This fails if somebody (such as filesystem) has already an exclusive ownership of the block device and thus prevents modifying the loop device under some exclusive owner which doesn't expect it.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2025-38709 since 04/16/2025. The exploitation appears to be easy. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 02/10/2026).

The vulnerability scanner Nessus provides a plugin with the ID 261541 (Linux Distros Unpatched Vulnerability : CVE-2025-38709), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.103, 6.12.43, 6.15.11, 6.16.2 or 6.17-rc1 eliminates this vulnerability. Applying the patch ce8da5d13d8c2a7b30b2fb376a22e8eb1a70b8bb/139a000d20f2f38ce34296feddd641d730fe1c08/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624/7e49538288e523427beedd26993d446afef1a6fb 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 (261541) and CERT Bund (WID-SEC-2025-1976). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

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

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.8
VulDB Meta Temp Score: 6.6

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

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / 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: 261541
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-38709

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.103/6.12.43/6.15.11/6.16.2/6.17-rc1
Patch: ce8da5d13d8c2a7b30b2fb376a22e8eb1a70b8bb/139a000d20f2f38ce34296feddd641d730fe1c08/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624/7e49538288e523427beedd26993d446afef1a6fb

Timelineinfo

04/16/2025 CVE reserved
09/04/2025 +141 days Advisory disclosed
09/04/2025 +0 days VulDB entry created
02/10/2026 +159 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-38709 (🔒)
GCVE (CVE): GCVE-0-2025-38709
GCVE (VulDB): GCVE-100-322570
CERT Bund: WID-SEC-2025-1976 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Entryinfo

Created: 09/04/2025 18:31
Updated: 02/10/2026 07:02
Changes: 09/04/2025 18:31 (60), 09/05/2025 19:03 (7), 09/08/2025 00:20 (2), 10/08/2025 17:55 (1), 12/03/2025 22:57 (11), 12/09/2025 18:13 (1), 01/15/2026 02:08 (1), 02/10/2026 07:02 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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