CVE-2025-40268: Linux kernel · cifs: client: fix memory leak in smb3_fs_context_parse_param
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6 : update Linux kernel when convenient.
Data as of 30 Oct 2026, 12:49 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- Patch
- Available – fixed in e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6, 4515743cc7a42e1d67468402a6420c195532a6fa, 868fc62811d3fabcf5685e14f36377a855d5412d +2
Exploitation evidence
Disclosed: evidence found.
CVE published 6 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
Description
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
References
- git.kernel.org/stable/c/299bc05e1475a4aa1eb985ade8f39e68c1bba9b9 (opens in a new tab)
- git.kernel.org/stable/c/868fc62811d3fabcf5685e14f36377a855d5412d (opens in a new tab)
- git.kernel.org/stable/c/48c17341577e25a22feb13d694374b61d974edbc (opens in a new tab)
- git.kernel.org/stable/c/4515743cc7a42e1d67468402a6420c195532a6fa (opens in a new tab)
- git.kernel.org/stable/c/e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6 (opens in a new tab)