Linux Kernel up to 6.6.116/6.12.58/6.17.8 cifs smb3_fs_context_parse_param memory leak

Summaryinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.6.116/6.12.58/6.17.8. The impacted element is the function smb3_fs_context_parse_param of the component cifs. This manipulation causes memory leak. This vulnerability is tracked as CVE-2025-40268. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.116/6.12.58/6.17.8. It has been declared as critical. Affected by this vulnerability is the function smb3_fs_context_parse_param of the component cifs. The manipulation with an unknown input leads to a memory leak vulnerability. The CWE definition for the vulnerability is CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: cifs: client: fix memory leak in smb3_fs_context_parse_param The user calls fsconfig twice, but when the program exits, free() only frees ctx->source for the second fsconfig, not the first. Regarding fc->source, there is no code in the fs context related to its memory reclamation. To fix this memory leak, release the source memory corresponding to ctx or fc before each parsing. syzbot reported: BUG: memory leak unreferenced object 0xffff888128afa360 (size 96): backtrace (crc 79c9c7ba): kstrdup+0x3c/0x80 mm/util.c:84 smb3_fs_context_parse_param+0x229b/0x36c0 fs/smb/client/fs_context.c:1444 BUG: memory leak unreferenced object 0xffff888112c7d900 (size 96): backtrace (crc 79c9c7ba): smb3_fs_context_fullpath+0x70/0x1b0 fs/smb/client/fs_context.c:629 smb3_fs_context_parse_param+0x2266/0x36c0 fs/smb/client/fs_context.c:1438

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-40268 since 04/16/2025. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 296481 (SUSE SLES15 Security Update : kernel (SUSE-SU-2026:0278-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.117, 6.12.59 or 6.17.9 eliminates this vulnerability. Applying the patch 868fc62811d3fabcf5685e14f36377a855d5412d/48c17341577e25a22feb13d694374b61d974edbc/4515743cc7a42e1d67468402a6420c195532a6fa/e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6 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 (296481), EUVD (EUVD-2025-201587) and CERT Bund (WID-SEC-2025-2756). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• NetApp FAS
• NetApp AFF
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Microsoft Azure Linux

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.116
• 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
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.12.55
• 6.12.56
• 6.12.57
• 6.12.58
• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3
• 6.17.4
• 6.17.5
• 6.17.6
• 6.17.7
• 6.17.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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