Linux Kernel up to 6.6.87/6.12.24/6.14.3/6.15-rc2 ksmbd smb_break_all_levII_oplock use after free

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.6.87/6.12.24/6.14.3/6.15-rc2. Affected is the function smb_break_all_levII_oplock of the component ksmbd. Such manipulation leads to use after free. This vulnerability is documented as CVE-2025-37776. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.6.87/6.12.24/6.14.3/6.15-rc2. Affected by this issue is the function smb_break_all_levII_oplock of the component ksmbd. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_break_all_levII_oplock() There is a room in smb_break_all_levII_oplock that can cause racy issues when unlocking in the middle of the loop. This patch use read lock to protect whole loop.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2025-37776 since 04/16/2025. The exploitation is known 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 03/16/2026).

The vulnerability scanner Nessus provides a plugin with the ID 240657 (Ubuntu 25.04 : Linux kernel vulnerabilities (USN-7594-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.88, 6.12.25, 6.14.4 or 6.15-rc3 eliminates this vulnerability. Applying the patch 296cb5457cc6f4a754c4ae29855f8a253d52bcc6/d54ab1520d43e95f9b2e22d7a05fc9614192e5a5/d73686367ad68534257cd88a36ca3c52cb8b81d8/18b4fac5ef17f77fed9417d22210ceafd6525fc7 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 (240657) and CERT Bund (WID-SEC-2025-0922). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Dell Avamar
• Open Source Linux Kernel
• IBM DataPower Gateway
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.6.50
• 6.6.51
• 6.6.52
• 6.6.53
• 6.6.54
• 6.6.55
• 6.6.56
• 6.6.57
• 6.6.58
• 6.6.59
• 6.6.60
• 6.6.61
• 6.6.62
• 6.6.63
• 6.6.64
• 6.6.65
• 6.6.66
• 6.6.67
• 6.6.68
• 6.6.69
• 6.6.70
• 6.6.71
• 6.6.72
• 6.6.73
• 6.6.74
• 6.6.75
• 6.6.76
• 6.6.77
• 6.6.78
• 6.6.79
• 6.6.80
• 6.6.81
• 6.6.82
• 6.6.83
• 6.6.84
• 6.6.85
• 6.6.86
• 6.6.87
• 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
• 6.14.0
• 6.14.1
• 6.14.2
• 6.14.3
• 6.15-rc1
• 6.15-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

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

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